KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 63. NtO 9. 13 



short. The alimentary canal is not fully differentiated, the rudiment of the heart is 

 distinguishable, as are also the peribranchial cavities on both sides of the body. 

 The most striking structures, however, are the generative organs, especially the 

 female ones. The rudiments of the testes are situated on each side, close to the 

 outer wall of the peribranchial sacs. They are only slightly 

 differentiated but are quite distinct. The female organs 

 are represented by two groups of eggs, one on each side; 

 some eggs are of large size, while others are small, but 

 all are well developed. They each represent, at least as 

 regards the larger ova, the rudiment of a one-egg o varv, J e xt-fig. 5 -Botryiius schiosseri Pallas. 



° ° ° x oung bud, seen from the ventral side. 



as will be shown in what follovvs. It should be noticed xso. o. Ovary. st. staik. t. Testis. 

 that they are situated on a level wifch the testes, and 



not behind them as in the above-described Metrocarpa, and also that they are enclosed 

 in wide dilatations of the body-wall, thus adding in a peculiar waj^ to the breadth 

 of the young zooid. The zooids are thus hermaphrodite; the male and female organs 

 are separated though situated close to each other, and they occur together in the 

 very young bud in an early stage of development. 



The presence of rudimentary testes in the bud seems to have escaped the 

 observation of Michaelsen, who as recently as 1921 investigated Botryiius schiosseri 

 also. Respecting the reproductive organs Michaelsen makes the following statement: 

 »Die Personen sind protogyn-zwittrig. Schon an ziemlich jungen Knospen findet man 

 jederseits ein dick linsenförmiges, die Leibeswand nach aussen aufbauchendes und zu- 

 gleich den Pribranchialraum verengendes Ovarium. Hoden findet man nur an aus- 

 gewachsenen Personen, — — — » (1. c. p. 111). 



Michaelsen's investigation does not agree either with Pizon's who pointed out 

 in his work entitled: »Histoire de la Blastogénése chez les Botryllidés» published as 

 long ago as 1893, that the genital glands of the Botryllidce are hermaphrodite and that 

 the male and female organs occur together in early stages of development. Though 

 the accuracy of certain details in the above-mentioned paper relative to the origin 

 and formation of the genital glands have recently been called in question, and even 

 impugned — no doubt with justification, though the critics have not succeeded in 

 adding anything positive — Pizon is right as far as his observation of the early occur- 

 rence of both male and female rudimentary organs is concerned. His statement, 

 howewer, to the effect that »chaque glande génitale est donc hermphrodite» (1. c. p. 19) 

 is far from indisputable, and it is not supported by what has been published by other 

 writers. The question of the origin and formation of the generative organs is still 

 unsolved, and hence we know nothing for certain as regards the hermaphroditism 

 of the glands; we are only justified in stating that the zooids are hermaphrodite. 



Stage II (Pl. 1, figs. 5 — 7. Text-fig .6). The presence of well-developed testes 

 even in the young zooid is unquestionable as appears from fig. 6. The individual here 

 figured in not fully developed - it hardly measures 1 mm. in length. It is shown 

 from the ventral side. It is noticeable that the reproduction by budding has already 

 commenced at this early stage: one small bud is to be seen on each side, the one on 



