70 



be relied upun and assigned a greater value than those 

 of most amateurs. 



THE AiniFhlAL r.MPKEiiXATIOX DF THE EGG. 



Tavo ripe males were selected, tlie si)ermatozoa from 

 wliicli was very active, and the visceral mass was cut 

 out : all parts of the digestive organs were then removed, 

 leaving the generative products in the saucer. The lat- 

 ter were then chopped up as linely as possible and mixed 

 with salt water, and the fragments of the digestive or- 

 gans, mantles and gills carefully washed out. and this 

 process was repeated several times until the male fluid 

 was free from all deleterious matter. Two female oys- 

 ters were then treated in a like manner, and Anally both 

 male and female fluids were mixed thoroughly in a glass 

 holding one half i^int of clean salt water. The fertiliza- 

 tion was accomplished at S.''.") P. M. on June Gth. The 

 following are the nottnl times of the principle changes 

 during the process of segmentation and subsequent de- 

 velopment : 



8.1:2 P. M. The eggs were irix^gular in shape and cov- 

 ered with spermatozoa — germinative vesicle x^l^inly vis- 

 ible — ax^pearance exactly as flgured by Brooks. (Report 

 Com. Fisheries. Maryland— PI. VIII— Fig. 51. 



8.32 P. M. Germinative vesicle had disappeared and 

 eggs nearly similar to Brook's flg. o'2, though not so reg- 

 ular in outline. 



The water was now siphoned off and the glass half 

 tilled with fresh sea-water. 



1O.03 P. M. One hour and flfty-three minutes after 

 fertilization, the eggs had become elongated, and the 

 polar globule was easily observed. In a few eggs the 

 separation of the micromeres and macromeres could be 

 distino'uished. The ai)i3earance of the eggs was as is 

 shown in Brook's flgs. 2. 3. 4 and o. the larger number 

 resembling flgs. 2 and 3. 



At 11.10. about three hours after fertilization, all the 



