FERTILIZATION ON PARTHENOGENESIS. 153 



5:00:20 P.M. Eggs and acid water poured into I liter of alka- 

 line sea water. 



(a) 97 per cent, of eggs possessed good membranes. 

 5:02:20 P.M. One part of (a) eggs shaken in test tube 12 times, 



poured into normal sea water. 



(&) 10 per cent, of eggs still possessed full or partial membranes. 

 5:05 P.M. (i) (&) eggs in 100 c.c. fresh sea water + 4 c.c. 



sperm suspension. 

 5:20 P.M. (2) (&) eggs in 100 c.c. fresh sea water + 4 c.c. 



sperm suspension. 

 5:23 P.M. (3) (a) eggs in 100 c.c. fresh sea water + 4 c.c. 



sperm suspension. 

 5:40 P.M. (4) (6) eggs in 100 c.c. fresh sea water + 4 c.c. 



sperm suspension. 

 5:45 P.M. (5) normal insemination control. 



After 3 hours the number of cleavages were noted and after 

 24 hours observations were made for swimming larvae. 



Cleavage Out of Swimming 



100 Eggs Counted. Larvae. 



I O O 



2 O 



3 i o 



4 o o 



5 95 85 estimated. 



Thus even though we have entirely deprived 90 per cent, of 

 the eggs of their membranes yet in no case did we have a single 

 egg showing cleavage after insemination. One per cent, of 

 cleavages were noted for the unshaken control and we see that 

 97 per cent, of the eggs formed full membranes. Cortical 

 changes though slight were appearing on the other eggs. 



The shaken eggs, (b) lot, cytolized even more rapidly than 

 did the unshaken (a) lot. This lot (a) still possesses its mem- 

 branes. 



Our conclusions from this, as well as from many other experi- 

 ments, can only be that these eggs, after production of full 

 membranes, are in an unfeitilizable condition. This condition 

 is not due to the presence of a so-called impermeable membrane 

 for that we have eliminated by shaking; neither is it due to 

 injury of the eggs through shaking for a large percentage of 



