STUDIES OF FERTILIZATION. 



There is thus an extraordinary contrast between fertilized 

 and unfertilized eggs in their sensitiveness to copper; it is 

 obvious that copper has an effect that belongs to a separate 

 order of sensitiveness on the early stages of fertilization as 

 compared with later stages. 



(b) The question thus arises as to the time limits of the early 

 inhibiting copper effect. A number of experiments were per- 

 formed to test this point, two of which are presented in Tables 

 II. and III. In these experiments the eggs were inseminated 

 in sea-water and then transferred at intervals to the copper 

 solution. Samples of the eggs shown in Table III. were trans- 

 ferred back to sea-water after fourteen minutes in the copper 

 solution to test their viability. 



TABLE II. 



(Exp. 12.) EFFECTS OF COPPER CHLORIDE ON EGGS INSEMINATED i.v SEA- 

 WATEU. A very heavy insemination was used in this experiment: two drops of 

 2 : 5 : 7.5 c.c. 



Transfers to Per Cent. 



1/500,000 CuCh. Segmented. Remarks. 



(a) 4 seconds after insemination 10% -f- Irregular cleavage. 



(&) 6 seconds after insemination io%+ Irregular cleavage. 



(c) 10 seconds after insemination 80-90% Irregular cleavage. 



(d) 20 seconds after insemination 80-90% Irregular cleavage. 



(e) 30 seconds after insemination 100% Irregular cleavage. 



(/) 60 seconds after insemination 100% Irregular cleavage. 



(g) Control in sea-water 100% Normal. 



(h) Control inseminated in the Cu 



solution I % Irregular cleavage. 



Here we must note two results particularly: 



(1) Eggs that have begun fertilization reaction before transfer 

 to the copper solution go through to cleavage, while those that 

 have not begun it are instantaneously inhibited. Transfers 

 made even four seconds after insemination (Table II.) include a 

 considerable proportion of eggs (varying with sperm concentra- 

 tion in various experiments from 5 to 25 per cent.) which complete 

 the fertilization and segment. The percentage rises to normal 

 with increase of time before transfer. 



(2) Eggs transferred from normal insemination to the copper 

 chloride within the first two minutes do not give a complete 



