SUSCEPTIBILITY IN EGGS OF AMPHITRITE. 37 



and examined. Care was taken to avoid disturbing those left in 

 the dishes. 



The control showed nearly all eggs unchanged ; in a few the 

 germinal vesicle had broken down and they were darker (more 

 opaque) in color ; a few had started to segment. 



Lot 2. The germinal vesicle had broken down in nearly all ; 

 a " perivitelline space" found in about 20 per cent., but was 

 rather small in most of this number. Most of the eggs were 

 light (translucent) in color. 



Lot 4. An irregular "perivitelline space" in 40-50 per cent. 

 The germinal vesicle was broken down in practically all, the 

 light-colored as well as the dark. There were a few extra-ovates. 



Lot 6. The germinal vesicle broken down in nearly all ; a 

 "perivitelline space" in 4050 per cent., irregular in some; a 

 smaller number are blackened. 



Lot 8. A prominent "perivitelline space" and contracted pro- 

 toplasm in 5060 per cent.; the rest have the germinal vesi- 

 cle intact. 



Anipliitrite eggs frequently begin differentiation if left in sea- 

 water entirely undisturbed. This is shown in the above control. 

 The experiment so far disclosed no marked phenomena, and I 

 give the above descriptions to indicate the comparatively uniform 

 development at this time. No evidence of normal segmentation 

 was found at any time in this and the three following experiments. 



All the dishes were again examined at 9:30 the next morning, 

 as the advanced stages afford a better means of testing the effects 

 of transference. Below is given the estimated number of ciliated 

 eggs found in 2,OOO of each lot. Aside from the swimming eggs, 

 the different lots were in practically the same condition as on the 

 previous evening. No further description is then necessary. 



Lot Time Transferred Number Ciliated 



Number. from Beginning. in 2,000 Eggs. 



1 O mill. O 



2 I? " O 



3 33 " i 



4 48 " 10 



5 6 3 " 4 



6 93 " 60 



7 123 " 10 



8 153 " 10 



