22O 



HELEN DEAN KING. 



in them. Presumably a slight amount of water was extracted 

 from the eggs by the salt solution; but, as the osmotic pressure 

 of sugar is so low, it is very probable that the chief action of the 

 sugar solution would be to prevent the eggs from absorbing water 

 during the fertilization period. 



The mortality among the tadpoles reared from the eggs that 

 had been subjected to the action of the salt solution was much 

 greater than when a sugar solution had been used. In both cases 

 the greatest mortality occurred during the first fortnight after 

 the experiment began. The embryos that lived beyond this 

 time seemed for the most part to have recovered from any inju- 

 rious effects of the treatment to which the eggs had been sub- 

 jected before fertilization. In their later development the 

 tadpoles in both lots appeared to be perfectly normal and of 

 average size. None of them showed any specific abnormalities 

 such as those Hertwig ('95), Gurwitsch ('95, '96) and Morgan 

 ('03) produced by subjecting the fertilized eggs of the frog or 

 of the toad to the action of solutions of various salts. 



The eggs used in these experiments were taken from the left 

 uterus of the female whose eggs, from the right uterus, were 

 employed in the experiments described in section 2; and they 

 were fertilized with spermatozoa from the male designated as 

 no. 2 in those experiments. The sex ratio in the lot of indi- 

 viduals, belonging to the former series, that developed from 

 eggs that were fertilized with spermatozoa from the same male 

 serve as a control for the present experiments (Table II.). 



Table IV. shows the results obtained in this investigation. 



TABLE IV. 

 EGGS TREATED WITH HVPERTONIC SOLUTION'S BEFORE FERTILIZATION. 



Both lots, as the above table shows, gave a percentage of 

 females that is considerably higher than that in the control. 



