1 8 E. E. JUST. 



summarized briefly as follows : In 95 per cent, sea-water eggs fer- 

 tilize normally as revealed by the per cent, of membranes formed. 

 They cleave and gastrulate in this dilution. In most cases the eggs 

 are scarcely to be distinguished from eggs inseminated in normal 

 sea-water. In 90 per cent, sea-water membranes are normal and 

 cleavage fairly normally; but these eggs form about 10 per cent, 

 exogastrulse. In 85 per cent, sea-water the per cent, of mem- 

 branes is close to normal — 95 per cent, or slightly more. The 

 cleavages show some abnormalities and the per cent, of exogas- 

 trulse is greater than in 90 per cent, sea-water. In 80 per cent, 

 sea- water the per cent, of cleavage falls and the per cent, of 

 exogastrulae increases. 



The experiments indicated that the dilution made up with 75 

 parts sea- water plus 25 parts tap water is the lowest which permits 

 cleavage. In this the gastrulse are very abnormal. We may, 

 therefore, turn our attention to the experiments made with this 

 and greater dilutions of sea-water. Eggs inseminated in dilutions 

 greater than those that permit cleavage separate membranes. 

 Even in the dilution made up of equal parts tap water and sea- 

 water some membranes separate, though these are often hard to 

 see. Eggs, therefore, will respond to insemination with at least 

 abortive cortical changes, though they can not cleave. I cite now 

 one experiment which was made — as the majority of these experi- 

 ments — on the eggs of three females. 



June 21, 3:30 P.M. Six series of dilute sea-water, each con- 

 sisting of 6 members, as follows : 



Equal portions of uninseminated eggs from each of 3 females 

 (A, B, and C) put in each dilution of sea-water to make Series \A, 

 IB, and IC, UA, UB, and IIC. 



Series I A, IB, and IC uninseminated. 



Series 1IA, 115, and IIC inseminated with same quantity of 

 sperm from one male. Inseminations in each series 5-25 seconds 

 after eggs in dilute sea-water. 



