Notes on the morphology of the Tunicata. 567 



Korotneff's several papers ^) are the most recent dealing with 

 this subject. This author denies Heider's contention that the smaller 

 blastomeres are difficult to distinguish from follicle cells, figuring and 

 describing them as distinctly ditierent, even in advanced embryos. 

 On this point, then, Salensky, Brooks and Korotneff agree in 

 opposition to Heider. 



As to the nature of the granular bodies in the protoplasm of the 

 blastomeres Korotneff says (Korotneff, 1896, p. 342): "In meiner 

 Schrift über die Embryologie von S. democraüca habe ich mich gegen 

 die Vermuthung von Heider, wonach diese Ablagerungen keine Dotter- 

 partikelchen , sondern von den Blastomeren verzehrte Follikelzellen 

 seien, ausgesprochen. Jetzt kann ich meine Meinung bekräftigen und 

 ganz positiv behaupten, dass in den als Dotterplättchen bezeichneten 

 Gebilden niemals eine Spur von Kernen zu sehen ist", which is 

 certainly true, at least for S. hexagona and S. pinnata, since these 

 granular bodies are not ingested cells, but ingested follicle nuclei, 

 as Brooks had shown, and as is evident in the material I have 

 worked upon. The needle-like bodies figured by Korotneff in the 

 protoplasm of the blastomeres of S. cordiformis-sonaria I have not 

 seen described before. They appear from his figures to be peculiarly 

 arranged chromatin particles within the ingested follicle nuclei. (Com- 

 pare Korotneff, 1896, tab. B, fig. 14.) 



Korotneff fully confirms Brooks' description (without however 

 mentioning Brooks) of the disintegration of the follicle cells in the 

 central region of the embryo, speaking of a retrogressive metamor- 

 phosis of the kalymmocytes, "welche ganz blass werden, sich schlecht 

 färben und zuletzt nur noch in Spuren zu erkennen sind. Kurz und 

 gut, die Kalymmocyten gehen ganz zu Grunde, und ihre Bruchstücke 

 dienen gewiss den Histogenen [blastomeres] als Nährmaterial" [by 

 osmosis]. (Korotneff, 1896, p. 335.) 



Korotneff denies Brooks' statement that the organs are blocked 

 out in follicle cells which later are replaced by blastomeres, saying 

 that the organ rudiments are from the first composed of blastomeres. 

 If he is not contending over definitions, his statements on this point 

 are difficult to understand, for his figures show with the greatest 

 clearness just the condition of affairs Brooks has described [Compare 

 Korotneff, 1897, tab. 18, fig. 5 (rudiment of cloaca composed of 

 follicle cells alone), fig. 6, 7 and 8 (rudimentary walls of amnionic 



1) KoEOTNEFF, 1893, 1895, 1896, 1897. 



