36 HARRIETT M. ALLYN. 



and 10 minutes showed some unsegmented swimmers, but those 

 left permanently went to pieces (as also in potassium chloride 

 permanently). Something resembling one large polar body was 

 formed in many eggs. Cytological study was not made of these 

 eggs, and therefore I cannot say positively whether it was a polar 

 body or only a small extra-ovate. Morgan ('oo) has said that 

 he got no polar body formation with sodium chloride in Chce- 

 topterus. 



B. Acids. Six different acids were used, three mineral, 

 n/io hydrochloric, n/2O sulphuric, n/io nitric, and three or- 

 ganic, n/io acetic, n/io butyric, and n/2O oxalic. The results 

 were not particularly satisfactory, and not many experiments 

 were made. It is possible that better results might have been 

 obtained with other concentrations or with different length of 

 application of the acid. The results were as seen in Table VII. 



Since polar body formation was not good and the appearance 

 of the eggs was not promising, and since others had tried acids 

 with little effect on Chatopterus I did not press the methods 

 further. No normal segmented larvae developed. As noted in 

 the table, eggs left in 2 c.c. of w/ioHCl + 100 c.c. of sea-water 

 permanently, formed a small number of swimmers. Eggs in I 

 per cent, of the n/io acetic acid in sea-water, for I or 5 minutes, 

 formed polar bodies only, but the same solution for 103/2 minutes, 

 or 5 per cent, of the n/io in sea-water, for 5 minutes, induced the 

 formation of a few unsegmented swimmers. Of the ineffective 

 acids oxalic was most promising, and should be tried further. 



Butyric acid was used only in connection with sodium chloride 

 and sodium hydroxide, as follows: 2.8 c.c. n/io C 3 H 7 COOH + 50 

 c.c. sea-water 2 min., followed by 200 c.c. sea-water 20 min., fol- 

 lowed by 8 c.c. of 2^/2 M NaCl + 50 c.c. sea-water 10, 20, 30, 40, 

 50 or 60 minutes. A very small percentage of partially differ- 

 entiated eggs, non-swimming, were found next morning and 

 one swimmer was observed in the 30-minute lot, but the hoped-for 

 cleavage was not obtained. 



The cytological effects of the acids were similar, in the swim- 

 mers, to the potassium chloride effects, but many of the eggs 

 which did not develop far presented a very different appearance, 

 seemingly characteristic of acid treatment. These eggs showed 



