HISTORICAL SKETCH 



21 



with the second male nucleus was in the nature of a growth stimulus 

 and could therefore be called "vegetative" fertilization. 



Parthenogenesis. About the same time that Nawaschin made 

 his discovery of double fertilization, two Swedish botanists, H. O. 



Fig. 20. Double fertilization in Scilla sibirica. A, one male nucleus in contact 

 with egg nucleus, another in contact with the two polar nuclei. B, sperm and egg 

 nuclei, more highly magnified. C, sperm nucleus in contact with two polar nuclei, 

 more highly magnified. (After Finn, 1931.) 



Juel (1898, 1900) and S. Murbeck (1897, 1901), were engaged in 

 studying the mechanism of parthenogenesis in Antennaria and Al- 

 chemilla. Some years earlier Kerner (1876) had noted that in An- 

 tennaria alpina male plants were extremely rare in nature but that 

 even unpollinated female plants were able to form seeds. Juel made 

 a thorough study of the development and showed that even when 

 staminate plants do occur, the pollen is either lacking or only feebly 



