THE ECTOPLASM 



plasmic structure of the Rhynchelmis egg is similar to that 

 recorded for the Nereis-egg by several workers beginning 

 with Goette^ and this in turn recalls Spengel's older descrip- 

 tion for the egg of Bonellia.^ 

 Also the Chaetopterus-egg has an 

 interesting ectoplasm,^ so too that 

 of Thalassema^ (Fig. 12). 



Among the great group of soft- 

 bodied animals, the mollusks, 

 including the clams, snails and 

 ink or cuttle fishes, the following 

 produce eggs in which the ecto- 



riG. 12. — Ectoplasm on the 



plasm has been observed to be living egg of Thdlassema mellita 



marked off from the endoplasm: (after Lefevre). 



Mactra" and Mytilus^ (clams), various species of Chiton^' 



Patella,^ (a snail) (Fig. 13), Dentalimn^ (a scaphopod) and 

 the cuttle-fishes (cephalopods).^" In the eggs of Mactra 



^ Goette, 1SS2; V. Wistinghausen, iSgi; Wilson^ iSg2; Hempel- 

 mann, igii; Lillie^ F. R., igi2. 

 2 Spengel, iSyg. 

 '^ Lillie, F. R., igo6. 

 ■* Torrey, igoo; Lefevre^ igoj. 

 ^ Kostanecki, igo^. 

 ^ Meves, igiS- 

 ^ Kowalewski^ iSjS. 

 ^ Patten, iS8^; Jorgensen, igij. 

 ^ Wilson^ igo4. 

 '" Bergmann, I.e. 



97 



