298 



EARLY DETERMINATION IN DEVELOPMENT 



Vegetalizing and animalizing agents act on molluscs. Working 

 with LiCl and other salts, Ranzi ( 1928 ) obtained a series of mon- 

 sters of Loligo vulgaris (cephalopod) ranging from convergent 

 eyes, to cyclopy, cyclopy with a small eye and anophthalmia 

 (Fig. 8). SCN~-treated embryos developed a large stomodaeum 

 (stomodaeum rudiment is between eye rudiments) (Ranzi, 

 1944). Studying embryos with duplicitas cruciata, Ranzi (1931) 

 reached the conclusion that in cephalopod embryos it is most 



Fig. 8. Li+ effects on Lolifio embryos: A, control; B, convergent eyes; 

 C, cyclopy; D, anophthalmy. (From Ranzi, 1928.) 



likely that an evocator is acting (entoderm?). I think that pos- 

 sibly in cephalopods a rudiment hyperdeveloped by SCN~ and 

 reduced by LiCl, as occurs for amphibian notochord, is involved. 

 However, I have never carried out direct research to study this 

 point nor have other authors investigated this problem. Thus 

 today we cannot state positively whether an organizer exists in 

 cephalopod embryos. Experimental embryology of cephalopods 

 must be reconsidered. A great deal of material is available and 

 may be handled quite easily. 



