NOTE ON THE NATURE AND SOURCE OF " PURPLE X.' 



137 



original volume) was then added so that the salt content might 

 equal that of the solution with which it was to be compared. 

 A series of experiments was then run in duplicate, using this 

 echinochrome on the one hand, and "purple x" on the other. 

 The addition of NaOH and HC1 to echinochrome gave the results 

 described by MacMunn. No visible change could be obtained 

 in the "purple x," however, by the addition of either reagent. 

 Thus it was established that, whatever the chemical nature of 

 "purple x" may be, it is not identical with echinochrome. 



III. PHYSIOLOGICAL EFFECT OF BOILED SPERM. 



The addition of boiled sperm suspension to eggs, in Arbacia, 

 causes the jelly surrounding the egg to swell, as can be demon- 

 strated by putting them into India ink. It also becomes more 

 sticky. As a result of this, the eggs adhere to each other and 

 to the bottom of the dish. When fresh spermatozoa are added, 

 many get caught in the jelly and form "halos," but some are 

 able to penetrate to the eggs, so that fertilization is not inhibited. 



However, when "purple x" is present in the boiled sperm, 

 fertilization by fresh sperm and auto-initiation by egg-secretion 

 is inhibited, as shown in the following table. The percentages 

 were all obtained by counting 200 or more eggs, and a vertical 

 column represents eggs from the same female, treated in dif- 

 ferent ways. 





UNIVERSITY OF MICHIGAN. 

 March 17, 1915. 



LITERATURE. 

 Glaser, Otto. 



'14 On Auto-parthenogenesis in Arbacia and Asterias. BIOL. BULL., Vnl. 



XXVI. 

 MacMunn. 



'85 On the Chromatology of the Blood of Some Invertebrates. Quart. Jour. 



Mic. Sci., Vol. 25. 



