MYRA MELISSA SAMPSON. 



An equal volume of sea-water was treated in the same manner 

 and used as a control. Unheated filtrate and unheated sea-water 

 served as additional controls. The results are given in Table IV. 



4 



jro 



K 



*0 



30 



JO 



10- 



fR 



K* * t i 8 K> 



GRAPH IX. Correlation between the duration of dialysis and the percentage 

 of ova divided and cytolyzed Arbacia. A = dialyzate from a 50 per cent, sperm 

 suspension. Duration of dialysis = twenty hours. B = dialyzate from a 50 per 

 cent, sperm suspension. Duration of dialysis = ten hours. C = sea-water dia- 

 lyzed for twenty hours against sea-water. 



Heating the filtrate as above indicated does not greatly affect 

 its power to produce segmentation and cytolysis of ova of the 

 same species. It should be emphasized that the hydrogen-ion 

 concentration and the osmotic pressure of these solutions are 

 like those of the sea-water controls. 



It is thus evident that filtrates and dialyzates of spermatozoa 

 of Arbacia contain some substance, not destroyed by heat, 

 which produces profound changes in ova of the same species. 



