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In this paper an account is given of the principal facts observer in the meiosis of Euryophthalmus rufipennis Laporte which afford some evidence in favour of the view held by the present writer in earlier publications regarding the existence of two terminal kinetochores in Hem ip ter an chromosomes as well as the transverse division of the chromosomes. Spermatogonial mitosis - From the beginning of prophase until metaphase nothing worthy of special reference was observed. At anaphase, on the contrary, the behavior of the chromosomes deserves our best attention. Indeed, the chromoso- mes, as soon as they begin to move, they show both ends pronouncedly turned toward the poles to which they are connected by chromosomal fibres. So a premature and remarkable bending of the chromosomes not yet found in any other species of Hemiptera and even of Homoptera points strongly to terminally localized kinetochores. The explanation proposed by HUGHES-SCHRADER and RIS for Nautococcus and by RIS for Tamalia, whose chromosomes first become bent late in anaphase do not apply to chromosomes which initiate anaphase movement already turned toward the corresponding pole. In the other hand, the variety of positions assumed by the anaphase chromosomes of Euryophthalmus with regard to one another speaks conclusively against the idea of diffuse spindle attachments. First meiotic division - Corresponding to the beginning of the story of the primary spermatocytes cells are found with the nucleus entirelly filled with leptonema threads. Nuclei with thin and thick threads have been considered as being in the zygotente phase. At the pachytene stage the bivalents are formed by two parallel strands clearly separated by a narrow space. The preceding phases differ in nothing from the corresponding orthodox ones, pairing being undoubtedly of the parasynaptic type. Formation of tetrads - When the nuclei coming from the diffuse stage can be again understood the chromosomes reappear as thick threads formed by two filaments intimately united except for a short median segment. Becoming progressively shorter and thicker the bivalents sometimes unite their extremities forming ring-shaped figures. Generally, however, this does not happen and the bivalents give origin to more or less condensed characteristic Hemipteran tetrads, bent at the weak median region. The lateral duplicity of the tetrads is evident. At metaphase the tetrads are still bent and are connected with both poles by their ends. The ring-shaped diakinesis tetrads open themselves out before metaphase, showing in this way that were not chiasmata that held their ends together. Anaphase proceeds as expected. If we consider the median region of the tetrads as being terminalized chiasmata, then the chromosomes are provided with a single terminal kinetochore. But this it not the case. A critical analysis of the story of the bivalents before and after the diffuse stage points to the conclusion that they are continuous throughout their whole length. Thence the chromosomes are considered as having a kinetochore at each end. Orientation - There are some evidences that Hemipteran chromosomes are connected by chiasmata. If this is true, the orientation of the tetrads may be understood in the following manner: Chiasmata being hindered to scape by the terminal kinetochores accumulate at the ends of the tetrads, where condensation begins. Repulsion at the centric ends being prevented by chiasmata the tetrads orient themselves as if they were provided with a single kinetochore at each extremity, taking a position parallelly to the spindle axis. Anaphase separation - Anaphase separation is consequently due to a transverse division of the chromosomes. Telophase and secund meiotic division - At telophase the kinetochore repeli one another following the moving apart of the centosomes, the chiasmata slip toward the acentric extremities and the chromosomes rotate in order to arrange themselves parallelly to the axis of the new spindle. Separation is therefore throughout the pairing plane. Origin of the dicentricity of the chromosomes - Dicentricity of the chromosomes is ascribed to the division of the kinetochore of the chromosomes reaching the poles followed by separation and distension of the chromatids which remain fused at the acentric ends giving thus origin to terminally dicentric iso-chromosomes. Thence, the transverse division of the chromosomes, that is, a division through a plane perpendicular to the plane of pairing, actually corresponds to a longitudinal division realized in the preceding generation. Inactive and active kinetochores - Chromosomes carrying inactive kinetochore is not capable of orientation and active anaphasic movements. The heterochromosome of Diactor bilineatus in the division of the secondary spermatocytes is justly in this case, standing without fibrilar connection with the poles anywhere in the cell, while the autosomes are moving regularly. The heterochromosome of Euryophthalmus, on the contrary, having its kinetochores perfectly active ,is correctly oriented in the plane of the equator together with the autosomes and shows terminal chromosomal connection with both poles. Being attracted with equal strength by two opposite poles it cannot decide to the one way or the other remaining motionless in the equator until some secondary causes (as for instances a slight functional difference between the kinetochores) intervene to break the state of equilibrium. When Yiothing interferes to aide the heterochromosome in choosing its way it distends itself between the autosomal plates forming a fusiform bridge which sometimes finishes by being broken. Ordinarily, however, the bulky part of the heterochromosome passes to one pole. Spindle fibers and kinetic activity of chromosomal fragments - The kinetochore is considered as the unique part of the chromosome capable of being influenced by other kinetochore or by the poles. Under such influence the kinetochore would be stimulated or activited and would elaborate a sort of impulse which would run toward the ends. In this respect the chromosome may be compared to a neüròn, the cell being represented by the kinetochore and the axon by the body of the chromosome. Due to the action of the kinetochore the entire chromosome becomes also activated for performing its kinetic function. Nothing is known at present about the nature of this activation. We can however assume that some active chemical substance like those produced by the neuron and transferred to the effector passes from the kinetochore to the body of the chromosome runing down to the ends. And, like an axon which continues to transmit an impulse after the stimulating agent has suspended its action, so may the chromosome show some residual kinetic activity even after having lost its kinetochore. This is another explanation for the kinetic behavior of acentric chromosomal fragmehs. In the orthodox monocentric chromosomes the kinetic activity is greater at the kinetochore, that is, at the place of origin of the active substance than at any other place. In chromosomes provided with a kinetochore at each end the entire body may become active enough to produce chromosomal fibers. This is probably due to a more or less uniform distribution and concentration of the active substance coming simultaneously from both extremities of the chromosome.

Spermatogonial chromosomes of Pachylis laticornis and Pachylis pharaonis begin anaphasic movement with both ends turned toward the same pole, maintaining this form util they reach the poles. This is a proof that they are provided with one kinetochore at each end. Additional proof for a longitudinal division of each longitudinal half of the anaphase chromosomes of the primary sper- matocytes is presented against the idea of a previous end-toend pairing at metaphase. The longitudinal split of the chromosomes of the secondary spermatocytes which used to be considered as tertiary split is therefore a true secondary split. The heterochromosome in both species passes undivided to one pole in the first division of the spermatocyte. In Pachylis laticornis it appears connected with the poles by means of two fibrils detached from each extremity, what may be considered as indicating a rather premature longitudinal spliting. The behavior of the heterochromosome of Pachylis pharaonis is highly interesting and affords one of the most beautiful evidences in favour of the dicentricity of the chromosomes. Really, in metaphase the heterochromosome appears at the equator of the cell with a more or less round shape. In the beginning of anaphase it becomes fusiform. As anaphase proceeds it distends itself between the autosomal plates forming a long fusiform bridge or sends toward the plates a thick chromosomal thread. The bulky part of the heterochromosome as it passes to one side it reincorporates the substance of the thread in this side. The thread in the other side, which becomes generally thiner, is left with its kinetochore in the cell at this side. The heterochromosome therefore becomes terminally monocentric in the first division of the spermatocyte. Some figures, however, suggest that the heterochromossome from time to time may pass with both kinetochores to one of the cells, as ordinarily happens in the case of Pachylis laticornis. Summing up, other things apart the behavior of the heterochromosome in both species studied here puts out of doubt the question of the existence of two terminally located kinetochores.

The male of Eneoptera surinamensis (Orthoptera-Eneopteridae) is provided with 9 chromosomes, that is, with 3 pairs of autosomes and 3 sex chromosomes. Spermatogonia. - The autosomes of the spermatogonia are of the same size and U-shaped. One of the sex chromosomes approximately equalling the autosomes in size is telocentric, while the other two are much larger and V-shaped. One of the latter is smaller than the other. The sex chromosomes as showed in Figs. 1 and 2 are designated by X, Yl and Y2, X being the larger V, Yl the smaller one and Y2 the rod-shaped. Primary spermatocytes. - Before the growth period of the spermatocytes all the three sex chromosomes are visible in a state of strong heteropycnosis. X is remarkable in this stage in having two long arms well separated by a wide commissural segment. (Figs. 4, 5 and 6). During the growth period Y2 disappears, while X and Yl remain in a condensed form until metaphase. These may be separated from one another or united in the most varied and irregular manner. (Fig. 7 to 12). In the latter case the segments in contact seem to be always different so that we cannot recognize any homology of parts in the sense os genetics. At diplotene Y2 reappears together with the autosomal tetrads. X and Yl may again be seen as separate or united elements. (Figs. 13 and 14). At later diakinesis and metaphase the three sex chromosomes are always independent from each other, Y2 being typically rod-shaped, X and Yl V-shaped, X being a little larger than Yl. (Fig. 15 to 18). At metaphase the three condensed tetrads go to the equatorial plane, while the sex chromosomes occupy any position at both sides of this plane. In almost all figures which could be perfectly analysed X appeared at one side of the autosomal plate an Yl together with Y2 far apart at the other side. (Figs. 16 and 18). Only a few exception have been found. (Figs. 17 and 19). At anaphase X goes in precession to one pole, Yl and Y2 to the other (Figs. 20 and 21). As it is suggested by the few figures in which a localization of the sex chromosomes different from the normal has been observed, the possibility of other types of segregation of these elements cannot be entirely precluded. But, if this does happen, the resulting gametes should be inviable or give inviable zygotes. Early in anaphase autosomes and sex chromosomes divide longitudinally, being maintained united only by the kinetochore. (Figs. 20 and 21). At metaphase the three sex chromosomes seem to show no special repulsion against each other, X being found in the proximity of Yl or Y2 indifferently. At anaphase, however, the evidences in hand point to a stronger repulsion between X on the one side and both Ys on the other, so that in spite of the mutual repulsion of the latter they finish by going to the same pole. Secondary spermatocytes. - At telophase of the primary spermatocytes all the chromosomes enter into distension without disappearing of view. A nuclear membrane is formed around the chromosomes. All the chromosomes excepting Y2 which has two arms, are four-branched. (Fig. 22). Soon the chromosomes enter again into contraction giving rise to the secondary metaphase plate. Secondary spermatocytes provided as expected with four and five chromosomes are abundantly found. (Figs. 23 and 24). In the former all chromosomes are X-shaped while in the latter there is one which is V-shaped. This is the rod- shaped Y2. In the anaphase of the spermatocytes with four chromosomes all the chromosomes are V-shaped, one of them (X) being much larger than the others. In those with five there is one rod-shaped chromosome (Y2). (Fig. 25), Spermatids. Two classes of spermatids are produced, one with X and other with Yl and Y2. All the autosomes as well as Y2 soon enter into solution, X remaining visible for long time in one class and Yl in the other. (Figs. 26 and 27). Since both are very alike at this stage, one cannot distinguish the two classes of spermatids. Somatic chromosomes in the famale. - In the follicular cells of the ovary 8 chromosomes were found, two of which are much larger than the rest. (Figs. 29 and 30). These are considered as being sex chromosomes. CONCLUSION: Eneoptera surinamensis has a new type of sex-determining mechanism, the male being X Yl Y2 and the female XX. The sex chromosomes segregate without entering into contact at metaphase or forming group. After a review of the other known cases of complex sex chromosome mechanism the author held that Eneoptera is the unique representative of a true determinate segregation of sex chromosomes. Y2 behaving as sex chromosome and as autosome is considered as representing an intermediary state of the evolution of the sex chromosomes.

In order to test Piza's conclusions regarding the dicentricity of Hemipteran chromosomes, two species of bugs of the family Coreidae, namely, Anasa sp. and Leptoglossus stigma (Herbst), are studied in the present paper. a) Anasa sp. - The male of this species has 21 chromosomes, that is, 20 pairs of autosomes and a single sex chromosome. The latter divides equationally in the first division of the spermatocytes and passes undivided to one cell in the second division. In this it moves with its longer axis parallelly to the spindle axis and shows fibrillar connections with both poles. Special attention was paid to the behavior of the chromosomes in the anaphase of the spermatogonia. As it was previously stated (Piza 1946 and 1946a) with regard to other species, the chromosomes are here attached to the spindle by both ends and begin to move toward the poles strongly curved to them. No intercalary fibers could be detected although their existente may not be denied by theoretical reasons developed in another paper (Piza 1946). Mitoses in somatic tissues of the embryo were equally studied. Careful examination of anaphase chromosomes in a great number of cells showed that the chromosomes behave exactly as in the spermatogonia, being equally attached to the spindle by the extremities alone and moving with their ends looking to the pole. A weak median constriction sometimes replaced by a slightly clearer space was observed in prometaphase and even in metaphase chromosomes of the spermatogonia as well as the somatic cells, having already been referred to in the case of Diactor bilineatus. (Piza 1945). Hemipteran chromosomes being considered as iso-chromosomes originated by a longitudinal spliting of the monocentric chromosomes resulting from the second division of the spermatocytes, the median aspect just mentioned may be regarded as the point of union of the separated halves. (See origin of dicentricity in Piza 1946). b) Leptoglossus stigma - This species has spermatogonia provided with 20 pairs of autosomes and one sex chromosome whose behavior differs in nothing from what was stated in regard of the preceding species. In the primary spermatocytes nothing meriting special mention was observed. Orientation, connection with the poles and movements of the sex chromosome in the secondary spermatocytes confirm the views already developed.

1) Tetraploid plants of cassava (Manihot utilissima Pohl) obtained by colchicine treatment are smaller than diploid plants and an analysis of their growing habits showed that tetraploid clones were not uniform and could be divided into two groups : group one : plants with stalks so thick as but shorter than the diploid plants: group two : plants wich stalks shorter as and thiner than the diploid ones (See tables 1 and 2). 2) Production of roots and stalks was studied in one experiment of randomized blocks and one vegetative cicle of the plants, (about 10 months); diploid clones are more productive and the tetraploid clones are very variable (Table 10). The Índice stalk/root weight is smaller in diploid clones, thus showing that production of roots in relation to stalks in the tetraploid plants is smaller than in diploid plants. Tetraploid plants are slower in growing habits during the beginning of the development (Figs. 18 and 20 to 24). 3) One experiment of randomized lines of 15 plants each and two vegetative cicles of the plants (about 20 months) confirms the results obtained in the experiment of one vegetative cicle regarding the production of roots and stalks. However, the indice stalk/root in plants with two vegetative cicles is the same (i = 0,30) for all clones (diploids and tetraploids) and is identical with the indice for diploid plants with one vegetative cicle, indicating that in plants with two vegetative cicles the production of roots in relation to stalks is the same both in diploid and tetraploid clones. 4) The production of roots and stalks was studied in one systematic experiment of 3 clones, in blocks of about 100 plants each: diploid clone n.° 8 and tetraploid clones n.° 2 and 6. The results obtained confirm the difference between tetraploid and diploid clones and also between the two tetraploid clones involved in the experiment (see table n.° 26 and figs. 25, 27 and 28.) The commercial value of tetraploid clones could be established only after other experiments (more tetraploid than diploid plants in the same area) since the production per plant of tetraploid clones is smaller than the diploid ones. The tetraploid clone n.° 6 has plants very small, of low production of roots and did not support field conditions. It is suggested that this clone should be good for horticultural conditions. 5) The starch contents is the same in all tetraploid and diploid clones studied (see table n. 28) and in two other clones of bitter cassava (n.°s 9 and 10) included for comparison in the analysis.

The main facts presented in this paper may be summarized as follows: 1) Corizus (Liorhyssus) hyalinus (Fabr.) has primary spermatocytes provided with 6 autosomal tetrads, one pair of microchromosomes and one sex chromosome. 2) The two microchromosomes present in this species sometimes appear at the primary metaphase as an unequal pair of minute elements. In the secondary spermatocytes the unique microchromosome present may be in the limit of visibility or entirely invisible. This invisibility may be partly due to a loss of colourability. 3) The sex chromosome divides transversely in the first division of the spermatocyte, passing undivided to one pole in the second one. In the latter it becomes fusiform in the beginning of anaphase revealing in this manner its dicentricity. In late anaphase it finishes by passing to one pole leaving in the other pole one of its kinetochores sometimes accompanied by a chromosomal fragment. 4) All the chromosomes divide transversely in both divisions, a diagram being enclosed to elucidate the question. 5) Spermatogonial chromosomes are provided with one kinetochore at each end, being curved toward the poles since the most beginning anaphase. 6) The following hypothesis is presented as an essay to explain the origin of microchromosomes: Since microchromosomes parallel sex chromosomes in most respects, as for instances in heteropycnosis and pairing modus, it seems highly probable that they originate from sex chromosomes. One may suppose that the ancestral form of a given species had a sex chromosome which used to lose a small centric fragment when it divided during meiosis. This fragment might well be at first an unstable one. Later, to compensate the effects of such a deficiency a mechanism arose through evolution which produced two useful results : a) the establishment of the fragment as a permanent structure of the cell nucleus and b) the acquirement by the sex chromosome of the faculty of passing to one pole without losing any of its ends.

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Studying the spermatogenesis of Leptysma sp. and Leptysma dorsalis, the writer was able to observe primary spermatocytes in anaphase with the heterochromosome in precession, synchronism or succession, confirming in this way what was observed by Prof. Piza in several other species of Orthoptera.

Cephalocoema borellii (Giglio-Tos) has 19 chromosomes, that is 9 pairs of autosomes and a single heterochromosome, the latter having been observed either in succession or in synchronism as was the case of the two other species studied by Prof. PIZA, namely Cephalocoema zilkari Piza and Tetanorhynchus mendesi Piza. (= Cephalocoema sica Serv.).

1) In a former paper (4), the segregations of spiny versus spineless fruits was described as caused by one pair of mendelian factors, but in view of the possible pratical importance of spineless fruits a more detailed study was thought desirable. We may distinguish three main types of the distribuition of spine among the different varieties in our collections: Spineles fruits (inerms), found in a number of varieties. "Bald" fruits (a type called "careca" or bald owing to the irregular distribuition of the spines, which were always absent in some parts of the fruits while otrer patches might contain spines. Spiny fruits which may be classified into two or more groups, according to the number of regularly distributed spines. 2) The cross (spineless fruits) x (fruits with regularly distributed spines) HARLAND (7), PEAT (9) e FERNANDES (3) observed a 1:2:1 segregations in F2 while GURGEL (4) and DOMINGO (2) find it difficult to distinguish the homozygous and heterozygous spiny types without counting the number of spines. Such counts and the results of a detailed statistical analysis are now given. They show that the results of the 1:2:1 segregations are somewhat modified by both phenotypic modifications of the number of spines. The latter are caused by modifier genes introduced by both parents. 3) The cross between plants with a regular and an irregular distribuition of spines showed that the latter condition is due to the presence of two recessive complementary factors. Thus we have in F2, 15 regular to 1 irregular or partially "bald", and in back-crosses segregations in acordance with the ratio 3:1. 4) The cross spineless x "Careca", gave, as might be expected a trifatorial segregation in accordance with the following formula. "Inermes" "Careca" P : ss CalCal Ca2Ca2 x SS ca1ca1 ca2ca2 Fl : Ss CalCal Ca2Ca2 (with regularly distributed spines) F2 : 45 S- Cal- Ca2- (spines regularly distributed). 3 S- calca1 ca2ca2 ,"Careca) 16 ss ("inermes").

The present work is destinated to prove that the castes : workers and queens, in Melipona bees are due to genetic factors and not to differences in food. 2) Material used: Hives of Melipona quadri-fasciata anthidioides (Lep. 1836), M. schenki schenki (Gribodo, 1893), M. fasciata rufiventris (Lep. 1836), M. quadri-fasciata vicina (Lep. 1836), M. marginata marginata (Lep. 1836), Apis mellifera (L. 1758). 3) It should be pointed out that in Melipona bees there are no royal cells for the queens, but all the cells are of the same size independently of being destinated for workers, queens or drones. The numerous queens which are born are killed soon after emerging from their cells. 4) Changes of feeding in quality and in quantity caused no variation of castes. The only variable factor is the size, which becomes bigger when the bee is well nourished. 5) The offsprings of 5 hives were examined : 3 of M. quadri-fasciata anthidioides (n.o 1, n.o 2 and n.o 3), 1 of M. quadri-fasciata vicina (n.o 4) and 1 of M. marginata marginata (n.o 5). Combs of about 40 cells were taken into laboratory and the type of bee registered immediately after emerging. The results of the counts were: BOX COMB WORKER QUEEN PERCENTAGE Σ X2 to 12,5% Nº 1 1th 69 8 10,4% 0, 3139 " 1 2nd 144 18 11,1% 0, 2856 " 2 1th 52 8 13,3% 0, 0384 " 3 1th 45 10 18,2% 1, 6736 " 4 1th 56 4 6,7% 1, 8686 " 4 2nd 29 4 12,1% 0,00432 Σ X2 to 25% " 5 1th 34 14 29,2% 0,44444 "5 2nd 83 27 24,5% 0, 0121 In the 4 first boxes there is a percentage of 11,63% queens and in the last there is a percentage of 25,95%. 6) These percentages are very near two genetical ratios: 12,5% or 7:1, and 25% or 3:1, which correspond to a trifactorial and a bifactorial back-cross. Carrying out a X² test no significant deviations were found ( X² to 12,5% and to 25% and table 1 to 4). 7) We suppose that the formula for the queen in the first case (11,65%) is: AaBbCc. Since the Melipona bees are arrhenotokous hymenopteres, the drones are haploid and may have any one of the following eight formulas, corresponding to the gonic segregation of the queem : ABC, ABc, Abc, Abc, AbC, aBC, aBc, abC, abc. Anyone combination of these males with the queen will give a segregation of 7 workers to 1 queen, since there is always only one triple heterozygote among the eight possible segregates (table 5). 8) In order to explain the second case, it is suffient to assume that in this species there are only two pairs of factors, the queen being the double heterozygote : AaBb, while the drones may have any one of the following constitutions: AB, Ab, aB and ab. Workers are again all diploids which are homozygous for one or both factors, for instance: AABB, AABb, AaBB, aaBb, AAbb, etc. (table 6). 9) It is suggested that the genus Melipona is an intermediary type between the solitary bees, where all females are fertile independently of their feeding, and the genera Apis and Trigona, where without special feeding all females are born sterile, while only specially fed females develop into fertile queens. 10) No speculations are put forward with regards to the evolutionary mechanism which may have been responsible for the development of the genetical determination of castes in Melipona, since it seems advisable point to extend the studies to other insects with complicated caste systems.

A very simple method for calculating poultry balanced ration is reported in this paper. A table giving the crude protein composition of the common feeding stuffs at different weight used in the ration is included. The rules for using it is discussed, all calculation being restricted to addition an subtraction. The balanced rations are easily calculated and the use of the method is recommended to poultry keepers.

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In this paper the author describes a very interesting case of union of two homologous chromosomes of the scorpion Tityus bahiensis just by the opposite extremities. The two normal pairs of chromosomes behave as ordinarily, the members of each pair showing at times a slight disturbance in their regular parallelism. The complex chromosome, on the contrary, behaves itself as if it were devoid of kinetochores, that is, it does not orient like normal chromosomes nor reveal any kind of active movement. The fusion of the chromosomes has resulted from terminal breakage at the opposite ends, the correspondig fragments having been found unpaired in a cell in which two pairs of chromosomes were present. Consequently, the compound chromosome, like the normal ones, is provided with a kinetochore at each one of the free ends. Being thus a centric chromosome its behavior, or more exactly, its kinetic inactivity may be compared with that of the monovalents found elsewhere in meioses. It is due o the failure of a partner. The fusion of two homologous chromosomes has transformed them into a new chromosomal unit in whose corresponding parts the ability of pairing was entirely abolished. This result is in full contradiction with the theory of a point-to point attraction between homologous chromosomes attributed to particular power of the genes, since, if genes really exist, being placed in their original loci, they would promote the union side by side of the members of the compound chromosome. If an attraction loci-to-loci should prevail the compound chromosome would be bent as in Fig. 8, C or form a ring similar to the loops observed in the inverted segment of sailvary chromosomes of Drosophila, as represented in the Fig. 8, D and this, in accordance with the order of the loci resulting from an union of corresponding or opposite ends of the fused chromosomes, as indicated in the Fig, 8 A and B. The evidence in hand points to a fusion by non homologous extremities. The expected rings, however, have never been found in metaphase plates. From this fact the author concludes that there is no point-to-point attraction between chromosomes, a conclusion in full agreement with the behavior of Hemipteran chromosomes which, in spite of geing composed of two equivalent halves do not bend in order to adjust the corresponding loci. (Cf. the papers on Hemiptera published by the author in this volume).

The Author concludes, in this contribution, the estudy he has been making since 1943, on the biological and ecological comportment of Apinagia Accorsii Toledo an of Mniopsis Glazioviana Warmg., Podostemonaceae wich are found attached to the rocks of Piracicaba Fall (Piracicaba, S. Paulo, Brazil). During the flood period, from October until March, the especies mentioned perform their vegetative development. Apigia Accorsii emittes stolons wich produce, laterally, rhizomes: besides, the still alive parts of the remaning rhizomes are regenerated. Mniopsis Glazioviana emittes hemicylindrical roots, the radicular buds of wich are capable of developing into new plants. For both especies, the germination of seeds may be effected in the following substrata : placents, capsules and pedicels of the fruits, vegetative residues and rhizomatic matter of Apinagia. Dehiscence of fruits takes place in contact with the air. Seeds adhere to the above mentioned substrata by means of a mucilage resulting from the transformation of its external tegument, in contact with water. The seedlings have no main root. A large number of root hairs develop around the hypocotyl; their function is fixation. The attachment of the plants to the rocks is made by means of root hairs and "haptera". The tranfer of young plants, which develop in the placents, capsules and fruits pedicels, etc., to the rocks takes place when they grow heavy enough as to bend the pedicels. The fruits and their parts contitute the best mean for the survining of the species in its habitat, for they are the only organs which stick to the rocks, after the complete destruction of the plant's bodies. The vegetative development is performed exclusively under water, while the floral cycle takes place as soon as the plants come in contact with the athmosphere, when they flower and fructiffy rapidly.