FERTILIZATION REACTION IN ECHINARACHNIUS PARMA. 1 9 



tion must occur after the formation of the polar bodies. Fer- 

 tilizin production, therefore, may be regarded as the sign of 

 physiological maturity. This is borne out by a study of the 

 parallel between fertilization capacity and fertilizin production. 

 Eggs incapable of fertilization either have produced no fertilizin, 

 unripe eggs, or have lost fertilizin, stale (washed) eggs. 

 i. Ovary Eggs and Dry Eggs. 



As has been mentioned above, by cutting up ovaries in sea- 

 water and straining the mass one may procure fairly clean egg 

 suspensions free from bits of tissue. These are the "ovary eggs." 

 Dry or shed eggs are those deposited by the animals in clean dry 

 dishes. 



"Ovary Eggs." -Different lots of "ovary eggs" vary greatly 

 with respect to the agglutinin production, as repeated observa- 

 tions showed. A ten per cent, suspension made up of eggs from 

 one female may give a positive reaction on 1/6,400 dilution while 

 another ten per cent, suspension from another female may show 

 little or even no agglutinative power. The capacity for fertiliza- 

 tion corresponds so that following insemination ninety per cent, 

 or more of the eggs with strong agglutination action cleave; 

 very few of the eggs of no agglutinative action cleave. This is 

 due to the fact that by cutting up the ovaries one obtains eggs 

 of different degrees of ripeness. One lot from a given female 

 may consist of fully ripened eggs while another lot contain scarcely 

 any ripe eggs despite their appearance. If after washing the 

 same pieces of ovaries several times, one collects eggs after each 

 washing, the percentage of fertilization drops with each washing; 

 the first lot of eggs is made up doubtless of those ready to be shed 

 and so are fully ripened; successive lots are less mature. More- 

 over, dishes of "ovary eggs" usually contain some ovocytes. 

 Without exception among these eggs those that fail to develop, 

 give off no agglutinin; but those that have great capacity for 

 fertilization show h'gh agglutinating power. 



"Dry Eggs." Dry or shed eggs are perfectly ripe, of high 

 agglutination action, giving practically one hundred per cent, 

 cleavage, beautiful large gastrulae, and vigorous hardy plutei. 

 The difference between these and "ovary eggs" is striking. 

 Apparently when eggs are shed they are fully ready for fertiliza- 



