140 The Mechanistic Conception of Life 



in these experiments was caused by star-fish blood which was 

 added with the sperm. 



That it is possible to separate a lysin from the sperm can 

 be proved for the eggs of another species of sea-urchins, namely, 

 Strongylocentrotus franciscanus, the eggs of which are very 

 sensitive to lysins. In these eggs it is possible to call forth the 

 membrane formation with a very dilute watery extract of the 

 sperm of star-fish which was killed by heating it to 60° C, or 

 more. Such eggs can be caused to develop into plutei by treat- 

 ing them after the membrane formation for a short time with 

 hypertonic sea-water. In the place of star-fish sperm the 

 sperm of other foreign species can be used. I have called forth 

 the membrane formation in the sea-urchin egg with the living 

 sperm of sharks or even roosters. Such eggs act as if only the 

 membrane formation with the aid of butyric acid had been 

 caused. At room temperature they begin to develop but they 

 are sickly and soon perish. If, however, they are treated 

 afterward with a hypertonic solution they develop into normal 

 plutei. In this case only the lysin entered the egg but not the 

 spermatozoon. It was, therefore, necessary to treat such eggs 

 subsequently with hypertonic sea-water in order to cause them 

 to undergo normal development at room temperature. 



VI 



The idea that a lysin contained in the spermatozoon is the 

 formative stimulus which causes the egg to develop can be 

 tested experimentally. We know that blood contains lysins 

 which destroy the blood corpuscles of foreign species, while 

 it does not destroy the cells of the same species. If the idea is 

 correct that the spermatozoon acts upon the egg through a 

 lysin which calls forth the membrane formation it should be 

 possible to call forth the membrane formation in the unferti- 

 lized egg of the sea-urchin by foreign blood and such is the case. 

 I was able to show three years ago that the blood of certain 



