THE HEMIMYARIA (SALPIDAE) CLEAVAGE. 421 



to disintegrate, while the embryo is built up by the gonoblasts which 

 form the greater part of all the later rudiments of organs. SALENSKY, 

 therefore, considers the embryonic development of the tialpidae as 

 a process intermediate between the development of an egg and 

 budding, beginning with a regular cleavage, but the resultant blasto- 

 meres play no further part in the development, the embryo being 

 for the greater part built up out of derivatives of the egg-follicle. 

 SALENSKY consequently describes the embryonic development of the 

 Salps as follicular budding. A pt^iori, SALENSKY' s view as to the 

 part taken by the follicle cells in the embryonic development of the 

 Salpidae must be regarded as extremely improbable ; it is also by no 

 means proved by what SALENSKY says of the decisive stages. We 

 must therefore for the present accept TODABO'S views as the more 

 probable.* 



We have already seen (p. 390) that SALENSKY also ascribes a considerable 

 part in the building up of the embryo of Pyrosoma to the immigrated follicle- 

 cells or kalymmocytes, and he has recently attributed to these cells a share 

 in the development of the cellulose mantle of Distaplia (No. 49, see also 

 p. 357). 



The shortening of the oviduct mentioned above (Fig. 210) is not 

 (hie merely to the dilation of its lumen and the consequent shifting 

 of the cells of its wall, but is also directly connected with the immigra- 

 tion of cells already described. In this way, a large amount of cell- 

 material is given off by the wall of the oviduct and the follicle to the 

 embryo. In its abbreviated condition, the oviduct forms a short wide 

 chamber (Fig. 211 A) communicating with the follicle through a 

 narrow aperture which, however, soon widens. The two cavities 

 finally unite to form a single capsule, the lumen of which is almost 



* [According to BROOKS and METCALF (Nos. I. and XXIV.) these kalym- 

 inorytes first block out the embryonic tissues and organs, but are eventually 

 replaced by blastomeres, after which the former degenerate and probably serve 

 as food-material for the latter cells. Even at an early stage kalymmocytes 

 degenerate and their nuclei migrate into the large blastomeres, forming the 

 so-called yolk-particles. HEIDER (No. XIII.), while agreeing that the kalym- 

 mocytes are taken up by the blastomeres, thinks that the entire cell, not merely 

 its nucleus, enters the protoplasm of the latter. KOROTNEFF (Nos. XXrz. and 

 XXIa.), however, regards the masses seen in the blastomeres as true yolk- 

 masses and not degenerating kalymmocytes. The last two observers regard 

 the latter cells as playing a passive r61e in the development and do not agree 

 witli BROOK'S view that the embryonic organs are blocked out in kalymmocytes. 

 According to these two authors, the embryo is made up of large and small 

 blastomeres and kalymmocytes, the small blastomeres being indistinguish- 

 able from the latter and hence, they suppose, BROOKS' and SALENSKY'S error 

 arose, the cells which the latter took to be kalymmocytes being in reality 

 small blastomeres. ED.! 



