S. RANZI 299 



Raven (1952) carried out extensive research on Limnaea stag- 

 nalis ( gasteropod ) . LiCl-treated embryos develop as exogas- 

 trulae ( Fig. 9 ) in which, as in those of ascidians, no entodermiza- 

 tion occurs, but the animal pole organs are reduced just as the 

 ciliar tuft of the sea urchin. Monsters with convergent eyes, 

 cyclopy, and anophthalmia have been described. Arendsen de 

 Wolff-Exalto ( 1947 ) did not notice any change in determination 

 due to NaSCN action. 



A comparison between the alterations noted in the two mol- 

 luscs has not been made. However, an outstanding fact is the 



Fig. 9. Topographical relationship in Limnaea exogastrulae: A, nor- 

 mally developed organ rudiments; B,C, reduced organ rudiments at the 

 animal pole; b.ec, large-celled ectodeiTn; en., entoderm; m., marginal 

 zone; s. ect. small-celled ectoderm; st, stomodaeum. (From Raven, 1952.) 



identity of the series of cyclopic monsters induced by LiCl in 

 both. 



It is difficult to carry out a comparati\'e analysis based on egg 

 organization. LiCl inhibits rudiment development at the animal 

 half in sea urchins and Limnaea. This does not occur in amphib- 

 ians and in Ciona in which LiCl affects the notochord that is 

 a rudiment on the equatorial level of the egg. As a result, an inter- 

 pretation on the basis of comparative morphology does not seem 

 possible. 



Differences in Proteins from Embryos Showing 

 Different Malformations 



Research carried out in our laboratory many years ago showed 

 that ions inducing colloid precipitation also induce vegetalization 

 in sea urchins (Tamini, 1943b) and cyclopic monsters in Am- 

 phibia (Tamini, 1943a). Conversely "swelling" ions induce sea 



