136 W. C. CURTIS. 



My material was prepared for the general anatomy rather 

 than for this particular point, and the egg capsules are greatly 

 shrunken, but as nearly as I can make out from a careful exam- 

 ination of the uterine eggs they are all in the condition above 

 noted, viz., a resting fertilized ovum plus the yolk cells and egg 

 capsule. In Cestodes having this mode of development, there- 

 fore, the eggs accumulate in the uterus, but do not develop until 

 they are laid by the proglottid. The resting stage is comparable 

 to the resting condition known in many forms which lay winter 

 eggs or eggs which develop only after a considerable time. In 

 any given proglottid such Cestode eggs are of diverse ages, de- 

 pending upon how long they have been in the uterus, but are all 

 alike inhibited from development until the proper conditions are 

 present. Upon contact with the external water this resting stage 

 is stimulated, or, we might say, some inhibition is removed, and 

 development ensues, continuing as far as the six-hooked embryo. 

 Whether there is some specific thing in the sea-water which can 

 be fixed upon as the stimulus to development I have not ascer- 

 tained, but it has seemed to me quite possible that the stimulus 

 can be located in some specific chemical constituent of the sea- 

 water. 



From what we know of other Cestodes it is unlikely that the 

 six- hooked embryo of Crossobothrium can develop further in the 

 water, and that if this embryo does not find the appropriate stim- 

 ulus for further development by meeting with its next host it must 

 perish. What this next host is one would perhaps discover as 

 much by accident as by the most persistent work. Could I 

 clearly demonstrate that the larva found in the squeteague is the 

 young of Crossobothrium ladniatmn and there is a good deal ot 

 general evidence that this is the case-- 1 think that the nature of 

 the squeteague's food (young herring, adult herring, menhaden, 

 etc. --Peck, "Sources of Marine Food," U. S. F. C. Bull., '95) 

 would lead us to suspect that the six-hooked embryo, instead of 

 passing directly to the squeteague, might have an intermediate 

 host like the menhaden, herring, or some fish which feeds upon 

 the microscopic elements in the sea-water. 



