ARTIFICIAL PARTHENOGENESIS 579 



namely, 50 cc. m/2 (NaCl + KCl + CaCl.) + 8 cc. 2^ m (NaCl 

 +KC1 + CaClo). From the hypertonic solution they were 

 transferred into normal sea water. The temperature varied 

 but little from 22°C. The results of the experiment follow. 



a. Eggs six minutes in the alkaline solution. Some of the 

 eggs which had been in NH4OH for six minutes developed as 

 far as the two or even the four cell stage, but no further. The 

 blp.stomeres of the segmented eggs fell apart. No larvae were 

 formed and the majority of the eggs remained unaltered. None 

 of the eggs that had been in KOH for six minutes segmented; 

 all remained unaltered. The eggs which did not segment had 

 no membranes. 



h. Eggs twelve minutes in alkali. A large percentage of the 

 eggs that had been twelve minutes in the NH4OH formed mem- 

 branes and segmented, and a few of these developed into larvae. 

 The eggs which had not formed membranes remained unseg- 

 mented and intact. 



The eggs which had been for twelve minutes in KOH formed 

 no membranes and did not segment or develop into larvae. 

 A few showed amoeboid changes preceding a possible cell divi- 

 sion. Practically all the eggs were intact on the following day. 



c. Eggs twenty-four minutes in alkali. The eggs that had been 

 in NHiOH for twenty-four minutes practically all forrned mem- 

 branes, segmented normally to a large extent, and formed larvae. 

 Many of the latter reached the pluteus stage, and swam at the sur- 

 face of the dish. 



Of the eggs that had been twenty-four minutes in KOH about 

 10 per cent formed membranes and began to segment, but did 

 not go beyond the first stages of segmentation. Ninety per 

 cent of the eggs formed no membranes, did not segment, and 

 remained unaltered. We shall see later that such eggs, upon 

 the addition of sperm, will develop into normal larvae, thus 

 indicating that the treatment with KOH did not affect them. 



d. Eggs forty-two minutes in alkali. About 90 per cent of 

 the eggs that had been in NH4OH for forty-two minutes formed 

 membranes, segmented and developed into swimming larvae. 

 Not so many reached the pluteus stage as in the previous lot. 



