632 



Chas. B. Wilson 



Experiment 2. Some Rana eggs in the 4 cell stage were 

 removed from the jelly, but left within the membranes, and placed 

 in EiNGER solution on March 27^^. 



They remained dormant for about two hours (this time is the 

 average for all the eggs, of course there were many variations due 

 to individual differences). They then gradually recovered and deve- 

 loped in all respects like those reared by Hertwig and others in 

 salt solution. 



In later development these eggs showed the appearance and 

 gradual growth of the cilia over the ectoderm very finely. It was 

 possible to verify upon them the ciliated tracts and currents given 

 by AssHETON for the same species. For twelve days there was 

 very little loss, but they then began to die quite rapidly and were 

 all dead by the 15*^ day. 



They were also considerably contorted as though the solution 

 had affected the pigment cells in different portions of the body un- 

 equally. In ordinary development individual pecularities are found 

 in eggs from different bunches i. e. those laid by different females. 



These solutions seem to magnify such pecularities, and this 

 factor must always be taken into consideration when comparing the 

 effects produced by the solutions. 



The development of different eggs in the same bunch is ap- 

 proximately uniform, and so the retarding influence produces nearly 

 the same effect upon them all. 



Experiment 3. Some Rana eggs in the 16 cell stage were 

 placed in Ringer solution under the same conditions as those of 

 Experiment 2. These remained dormant for a slightly longer period. 

 This may have been due in part to individual differences in the two 

 bunches of eggs, but subsequent experiments go to prove that it was 

 partly also the result of their advance in development. 



The solution seemed to have more influence over the yolk cells 

 in these eggs and an enormous yolk plug protruded from the blasto- 

 pore. The pigment was unable to cover this surface and so it re- 

 mained light colored at the center, with numerous dark streaks 

 running over it around the border. Ten individuals (162/3%) out 

 of this lot were developed to the appearance of the external gills, 

 which occurred on the 15'^^ day. These were then preserved for 

 further examination. 



The proportion of eggs which died during development was much 

 larger than in either of the previous experiments. 



