304 I.OEB. 



death of the unfertilized egg are enzymatic (autolytic?) processes 

 which can he inhibited through poisons such as KCN. 1 



We did in fact succeed in showing that the addition of a small 

 amount of KCN to the unfertilized starfish eggs markedly 

 lengthens their life. Even after seven days such eggs can be 

 fertilized as soon as they are returned to normal sea water. We 

 also pointed out that, because of the well-known bactericidal 

 properties of potassium cyanide, the experiments on sea-urchin 

 eggs were not in themselves decisive and so began 'experiments on 

 starfish eggs 2 which, however, we were not able to complete at 

 that time. In dealing with eggs which are as long lived as sea- 

 urchin eggs a great development of bacteria in normal sea water 

 can not be prevented, since a few of the eggs always die and so 

 serve as an excellent culture medium for the further development 

 of bacteria. It need, therefore, surprise no one that the unfer- 

 tilized eggs of sea-urchins, as I was able to show this year, live 

 in sterile sea water for five days, or possibly longer, while they 

 die much earlier in ordinary sea water (about two days). The 

 very fact that the eggs of sea-urchins are found mature in the 

 ovary indicates that they are able to live a considerable time after 

 maturation and that they differ in this respect from the starfish 



egg- 



It is, however, a fact that in the same sea water the fertilized 

 and developing sea-urchin eggs live longer than the unfertilized 



eggs. 



It almost seems as if in certain of the higher animals there are 

 eggs which develop only when they are fertilized immediately 

 after leaving the ovary. Under the direction of Professor C. O. 

 Whitman, Harper has shown that the eggs of pigeons are fer- 

 tilized the moment they leave the ovary. The sperm lives in a 

 gelatinous mass upon the surface of the ovaries," so that provision 

 is made for the necessary contact between sperm and egg. This 

 also does away with the difficulty which many have found in 



1 Loeb and Lewis, American Journal of Physiology, Vol. VI., 1902. 



2 Loeb and Lewis, American Journal of Physiology, Vol. VI., 1902. 



3 Spermatozoa are in general much longer lived than eggs, even though 

 great differences exist in this regard in different animals. In the spermatic 

 vesicles of the queen bee spermatozoa are believed to remain more than a year 

 after copulations. 



