Phylum XV 



Mollusca, Class Amphineura 



CHAETOPLEURA APICULATA 



Benjamin H. Grave, De Pauw University 



Chaetopleura api-culata is a small species of chiton which occurs 

 abundantly in Vineyard Sound near Woods Hole, Massachusetts, and is 

 collected by dredging. The breeding season begins about June 25 and 

 extends to September 25. It is at its height during July and the first 

 half of August. Spawning takes place at night from 8 to n p.m. 



METHOD OF OBTAINING EGGS 



To obtain eggs and sperm, place 25 or 30 chitons in a large crystalliza- 

 tion dish and keep in running seawater during the day. They cling 

 to the bottom and sides of the dish and creep about more or less. Toward 

 evening wash free of sediment and place the containing dish, half filled 

 with seawater, on a laboratory table and allow to remain undisturbed. 

 It is sufficient if the chitons are well covered with water. About 8 p.m. 

 the males may be expected to begin to extrude sperm into the water and 

 half an hour later a few of the females spawn. 



For some reason many more eggs are shed during the second night 

 after collection than the first. A few are likely to be spawned the third 

 night, but after that a new collection of animals should be made. 



It has been observed in some species of mollusk that sperm in the 

 water stimulates the female to shed her eggs. For instance, Galtsoff 

 showed that this is the effective stimulus in the oyster. Metcalf made 

 the observation that when an aquarium contains both male and female 

 chitons the sperm is always shed before the eggs and he interpreted the 

 phenomenon as due to a chemical stimulus between the sexes. How- 

 ever, female chitons will spawn when isolated so that it is possible to 

 obtain unfertilized eggs if desired. 



CULTURE METHODS 



After spawning is completed the eggs may be taken up in a pipette 

 and transferred to fresh dishes of seawater. They should be washed 



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