400 T. H. MORGAN AND UM^ TSUDA. 



Hydrochloric acid, -^ per cent, . . Died. 



Sodium hydroxide, J^ per cent. . . Some died, in others the blasto- 



pore closed. 

 Corrosive sublimate, -Jq per cent. . Died. 



Curari (weak solution) . . . Nearly normal. 



Quinine, '02 gr. to 500 c.c. HgO . . Normal. 



Morphine „ „ . . Nearly normal. 



Strychnine (only partially dissolved) . Normal. 

 Alcohol, 10 per cent. . . . Developed very little. 



,j 5 „ . . . More than last, but died (un- 



closed blastopore). 

 „ 2^ „ . . . Developed partially (closed). 



Sodium chloride (3 grms. to 500 c.c. HjO ") Gave the desired result. Blasto- 

 = J strength of sea water ) pore open, 

 i „ „ . Normal. 



4 » „ . Died. 



Of the solutions given only one gave the desired result, 

 although the alcoholic solutions seemed to have a similar ten- 

 dency. The series in which *6 per cent, salt was used produced 

 the embryos to be described below. This happened boih for 

 the frog's and the toad's eggs, and was repeated with similar 

 results. Success depends on using exactly the right amount of 

 salt. Too much kills ; too little does not afifect the embryo. 

 To ensure success a series of trials should be made approxi- 

 mating to the '6 per cent, solution. 



In a second series of experiments the recent suggestion of 

 Herbst was followed. Embryos were placed in solutions of 

 salts of barium, calcium, sodium, and potassium. Three sets 

 of each solution were used, one stronger, one weaker, and one 

 the same strength as the '6 per cent, solution. 



Although in some of these solutions embryos with large 

 blastopores were produced, no particular relation was found 

 between the formation of abnormalities and the series of com- 

 pounds used. The best results were again in the sodium 

 chloride. 



Fig. XIV shows an embryo as seen from in front. A narrow 

 pigmented line marks the position of the suckers. Between 

 this and the white a thick fold of ectoderm marks the anterior 

 end of the medullary folds. The fold continues on each side 



