252 



GREGOR T. POPA. 



urchin eggs have been for a short time. The reaction is in- 

 stantaneous. The spermatozoa exhibit great activity and bunch 

 together, for a while, in compact clusters of various sizes. 



What is the immediate cause of the agglutination residing in 

 the spermatozoa? Is it due to a change in the arrangement of 

 the substances, or to an active elimination of the sticky substance 

 observed in fresh suspensions of spermatozoa? 



FIG. 10. Arrangement of agglutination experiment; a, egg-water, b, clusters- 

 c, sperm-suspension, d, drop of Janus green. 



One drop of egg-water and one drop of sperm suspension are 

 placed on a slide (Fig. 10). A very narrow bridge is established 

 between the two drops. Immediately the agglutination takes 

 place where the drops meet, and slowly spreads, so that we have 

 again various stages of a phenomenon on the same slide. 



At the left end of the egg-water drop (Fig. 10) the fluid is 

 still clear; at the middle, agglutinated clusters of spermatozoa 

 in great activity; at the right side of the sperm suspension drop, 

 the spermatozoa in various degrees of motion, are in a homo- 

 geneous suspension. 



In these conditions, one keeps the slides various lengths of 

 time (i-io minutes). Afterwards one puts very carefully a cover 

 slip with another drop of egg-water underneath (to mitigate the 

 power of capillarity). Many bunches of spermatozoa are spread 

 out, but many other resist, and one can observe, under the oil 

 immersion lens, what happens in the clusters. 



A long series of transformations of the individual spermatozoa 

 occur, represented by the next sketch (Fig. n). These trans- 

 formations take place under the influence of egg-water only. 

 But in order to see them more clearly, one may add at the 

 margin of the cover slip a drop of I per cent. Janus green in 



