6 E. E. JUST. 



terfere with the further development. I have never been able to 

 get more than twenty per cent, of these eggs to reach the swim- 

 ming stage. If one could determine definitely the quantitative 

 relations this percentage might be increased. From the observa- 

 tions it appears that the optimum amount of warm water used 

 varies; it depends upon the bulk of the eggs. While best results 

 are got with small quantities of water, it is possible to use too 

 little — three c.c. for instance, for the eggs for a large female. 

 Jelly formation and cleavage are induced but swimming forms 

 are less numerous than in the case of ten c.c. for about the same 

 bulk of eggs. 



The following are typical experiments of this group : 



(a) July 1 6, 10:30 A.M. Eggs from a dry female in a dry 

 watch glass are divided into two lots; one lot washed, the other 

 transferred to 5 cc. of sea-water at 34° C. Samples out as follows : 

 at 10:20, 10:50, and at five-minute intervals thereafter to 11:20. 



2:00 P.M. Uninseminated control, no change. Every single 

 warmed egg had formed jelly: all have formed polar bodies. At 

 least half of these are in cleavage stages. 



July 17. All dry eggs in some stage of cleavage, many of 

 which are normal; some swimming forms in many of the dishes 

 even after forty minutes' exposure. 



(&) July 17, 9:58 A.M. Eggs from a dry female divided into 

 two lots. Lot ^ in 5 c.c. of sea-water ; Lot B in 20 c.c. of sea -water. 

 Both exposed to 33° C. 10:01 jelly formation. Eight samples 

 taken as follows: 10:05, io:il, I0:i6, 10:22, 10:27, lO^SS- 10:38) 

 and 10:43. 



Lot A gave at least 95 per cent, of cleavage and a percentage 

 of swimming forms in all dishes beginning with No. 3 (the 18- 

 minute exposure). Lot B gave 75 per cent, of cleavage and best 

 swimmers for 24, 29, and 35-mInute exposures. 



(c) Other experiments showed that the highest per cent. 

 (100 per cent.) of jelly formation and of cleavage (98 to 99 per 

 cent.) is in the smaller quantities of sea-water — 5, 6, and 10 c.c. 

 — whatever the temperature ; a few swim. With larger quantities 

 of sea-water at the various temperatures more eggs remain in 

 the germinal vesicle stage. The lower exposures give most 

 normal-looking swimming forms — trochophores scarcely to be 



