FERTILIZATION REACTION IN ECHINARACHNIUS PARMA. l"J 



the cessation of fertilizin production would not prove that the 

 jelly forms fertilizin. However, after both acid treatment and 

 gentle shaking the eggs still produce fertilizin. 



Echinarachnius eggs may be shed without jelly. Often in a 

 given lot of eggs some will be found without jelly, and on three 

 occasions during the summer I observed eggs shed not one of 

 which had a jelly covering. These eggs proved to be normal in 

 every respect; secreted fertilizin, w r ere capable of fertilization, 

 and of normal development. 



I cite three experiments: 



1. One c.c. of dry eggs was placed in 50 c.c. of sea-water plus 3 c.c. of n/io HC1. 

 Gently stirred to prevent clumping and washed in four changes of sea-water. 

 Left in 50 c.c. of sea-water. Examination revealed absence of jelly in most eggs. 

 Tested after one hour, the egg water gave an 8-second reaction at 1/200 dilution. 



2. One c.c. of eggs was gently shaken five or six times in 10 c.c. of sea-water. 

 Most of the eggs lost their jelly. The eggs were washed 5 times in 10 c.c. of sea- 

 water and left finally in the cylinder in 10 c.c. of clean sea-water. On settling the 

 eggs were at the o.5-c.c. mark; tested, the supernatant sea-water gave at 1/400 

 dilution a 6-second reaction. 



3. One c.c. of dry eggs shed without jelly was placed in 24 c.c. of sea-water. 

 Tested an hour later the egg-water gave at 1/1,600 dilution a 6 second reaction. 

 After a sixth washing in 3 hours these eggs produced agglutinin giving an 8-second 

 reaction at 1/800 dilution. 



Whatever may be the interpretation of the experiments with 

 eggs freed of jelly through shaking or acid treatment, the con- 

 clusion drawn from the results with these eggs lacking jelly when 

 shed is inescapable: in Echinarachnius as in Arbacia the fertilizin 

 is secreted by the egg, however much the jelly may be loaded 

 with it. 



(b) Study of Immature Eggs. During the season one may al- 

 ways obtain immature sand-dollars. Indeed one gets the im- 

 pression that there is a rhythm in the breeding season. Loeb's 

 observations ('15) would suggest that this is true of the Cali- 

 fornia urchin, while Tennent 1 has noted the phenomenon which 

 suggests lunar periodicity in the breeding of the Atlantic urchins. 

 I was able, therefore, early in the season to determine quite 

 definitely that immature Echin arachnitis eggs do not give off 

 fertilizin. Thus, on July 3, immature eggs from three females 



1 Dr. Tennent also tells me that in Greece the gonads of urchins used as food 

 appear on the market only during certain moon phases; at other times the animals 

 are spent. 



