638 



Chas. B. Wilson 



Experiment 11. Some Chorophilus and Ambly stoma eggs, each 

 in the 64-cell stage, were placed together in a 0.6% salt solution 

 on March 28*^\ Again the Amblystoma eggs remained dormant for 

 some time (in this case 5 hours) while those of Chorophilus continued 

 developing with scarcely a break, but very soon a marked difference 

 between the two species became apparent. 



Both kinds of eggs were at the same stage when placed in the 

 solution, and according to the normal rate already given the Choro- 

 philus eggs should have developed much more rapidly than those 

 of Amblystoma. Such was not the case, however; they kept along 

 very evenly for a day, and then the Amblystoma eggs gained slowly 

 on the others and eventually reached gastrulation nearly 24 

 hours ahead of them. 



The Chorophilus eggs which should have gastrulated within 

 12 hours did not reach that period until the 5*^ day, while the 

 Amblystoma eggs that should have formed the blastopore on the 

 second or third day were only delayed till the fourth day. 



Moreover the Chorophilus eggs were very much shrunken and 

 contorted, especially around the head and anterior end, this portion 

 of the body being covered with ridges and small papillae. 



The yolk plugs were very large and showed the same pigment- 

 ation as has already been noticed in the case of Amblystoma and 

 Eana, though not quite so clearly. 



These Chorophilus eggs lived for 15 days and in that time 

 had not completed their gastrulation. The Amblystoma eggs on the 

 contrary, developed with some loss up to the formation of the external 

 gills when the few that were left were preserved. 



In this experiment, therefore, the effect of the same solution 

 under the same conditions was very different in the two kinds of 

 eggs, and was the same as that obtained in the previous ex- 

 periment. 



Experiment 12. In connection with the fact that it was found 

 so difficult to develop the Chorophilus eggs in any of the solutions 

 beyond the gastrula period, the following experiment is of special 

 significance. 



It was suggested by the results obtained by Davenpoet and 

 Neal in the » Acclimatization of organisms to poisonous chemical 

 substances « (9). 



Some unsegmented eggs of Amblystoma, Kana and Chorophilus 

 were placed in a 0.05% salt solution on March 29*^. 



