STUDIES IN ARTIFICIAL PARTHENOGENESIS. 15! 



membrane which becomes lifted from the surface of the egg as 

 the fertilization membrane. 



A study of the chemical behavior of the membrane gave 

 results of interest. Dilute acids cause it to swell. When one 

 part of normal HC1 is diluted with 9 parts of sea-water the 

 resultant solution causes a marked swelling. The membrane 

 becomes sticky and agglutination follows. 1 Dilute solutions 

 of nitric, butyric, and valerianic acids give similar results. As 

 far as can be ascertained however, this acid swelling of the mem- 

 brane does not result in complete solution. On the other hand 

 dilute alkaline solutions, although they cause little if any swelling 

 of the membrane, are quite effective in dissolving it away. In 

 order to study the effect of alkali on the membrane, it is best 

 to shake the jelly off the eggs first, as this often becomes 

 saturated with the Mg (OH) 2 precipitated by the alkali, and 

 obscures the result. Eggs in 50 c.c. of sea- water plus 2.5 c.c. 

 n/io NaOH soon become sticky; they cling to the bottom 

 of the dish and to each other. Soon the exterior surface of 

 the egg becomes rough, it is evidently no longer surrounded 

 by a membrane (and it is only prevented from diffusing through 

 the sea-water by coagulation). Many salts exert a swelling 

 effect on the membrane, and in some cases this is accompanied 

 by a complete solution of the membrane. When eggs are 

 dropped into 0.55 N Nal, the swollen membranes are very ap- 

 parent after 10 or 15 minutes have elapsed. In 40 minutes 

 almost all of the eggs are no longer surrounded by a membrane, 

 the periphery of these eggs instead of being smooth, now pre- 

 sents a roughened appearance. It is quite evident that the 

 protoplasm is naked and that the membrane has been completely 

 dissolved away by the sodium iodide. This behavior of the 

 membrane towards acids, alkalis, and salts, indicates its protein 

 nature. 



That it is not a lipoid is evident from the fact that it is insoluble 

 in any of the ordinary lipoid solvents. It might however contain 

 an admixture of lipoids. This is rendered improbable by the 

 following line of evidence. As was pointed out above, the almost 

 invisible character of the membrane indicates that its refractive 



1 Loeb ('08) described agglutination in HC1. 



