70 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



B. alba selfed = all ^ 



B. dioica 9 X B. alba cf = Fi all females. 



B. alba 9 X B. dioica cf = Fi 50% males + 50% females. 



B. dioica 9 X B. dioica cf = 50% males + 50% females. 



The hybrids produced are sterile. 



Correns's interpretation of his results is represented as follows: 



B. dioica 9 has gametic constitution 9 9 



B. dioica cf " " " 9 cf male dominant. 



B. alba 9 " " " S 



B. alba cf " " " y 



Bateson's objection to the above schematic representation of 

 Correns is that it ignores entirely any degree of maleness in the 

 pollen of Bryonia alba in contrast to the dominance of maleness 

 in B. dioica male. 



Bateson's interpretation of his results is represented as follows: 



B. dioica 9 has egg cells 9 and cf 



B. dioica cf " pollen all cf 



B. alba has egg cells 9 and cf and pollen all 9 



Strasburger, following Noll, has proposed the conception that 

 in dioecious plants the female has egg cells with only female 

 tendencies. The male gametes are of two strengths — strong and 

 weak. The assumption is made that the weaker of the two kinds 

 of male gametes in fertilization is weaker than the female gamete 

 and hence a female plant results; the fertilization of the egg of a 

 female plant by a strong male gamete results in a male plant. 

 Strasburger arrived at the above conclusions from an extended 

 study on dioecious forms. His conceptions were strengthened by 

 the behavior of his cultures of male and female plants of Afer- 

 curialis annua. The interesting observ^ations of Kriiger's in 1908 

 who reports that his so-called parthenogenetically produced seeds 

 on female plants of Mercurialis annua, upon germination produced 

 only female plants, were a confirmation of Strasburger's earlier 

 observations on the same form. The further confirmation of 

 these results by Bitter in 1909, who reports that the seed of his 

 self-fertilized female plants of Mercurialis annua produced 723 

 female and 21 male plants left no room for doubt as to the behavior 

 of these female plants. 



