90 Specificity in Fertilization 



found in addition that if the eggs of Ciona are put for 

 about ten minutes into a two per cent, ether solution 

 in sea water in a number of cases the percentage of 

 eggs fertilized by sperm of the same individual shows 

 a slight increase. Fuchs' has reported results similar 

 to those of Castle and Morgan. 



A new point of attack has been introduced into the 

 work of self-sterility in plants by the consideration 

 of heredity. Darwin found that in Reseda which is 

 monoecious (or hermaphroditic) certain individuals are 

 either completely self -sterile or completely self -fertile; 

 and Compton showed that apparently self-fertility 

 is a Mendelian dominant to self -sterility.^ 



According to Jost this self-sterility in hermaphroditic 

 plants is due to the fact that if pollen of the same plant 

 is used the normal growth of the pollen tube is inhibited, 

 while this inhibition does not exist for pollen from a 

 different individual. Correns calls these substances 

 which prevent the adequate growth of pollen, ''inhibit- 

 ory'* substances, and finds that they can apparently 

 be transmitted to the offspring. He made experiments 

 on Cardamine pratensis which is self -sterile. ^ He fertil- 

 ized two individuals of Cardamine crosswise and raised 

 sixty plants of the first generation. He compared the 

 fertility of these Fj plants toward (a) their parents, and 



»Fuchs, H. M., Jour. Genet., 1915, iv., 215. 



' Quoted from Fuchs. 



3 Correns, C, Biol. Centralbl., 1913, xxxiii., 389. 



