14 



The Journal of Heredity 



STI(;A1A of a PlAlPkLN FLOW KK 



It is upon the rough, sticky surface of this irregular body that the male iJoUcn grains 

 fall and germinate. Each one sends out a tube which grows down into the 

 tissue of the stigma (see the following figure) and finally reaches the ovary which 

 lies below. The nucleus of the pollen grain slips down this tube, comes in con- 

 tact with one of the ovules in the ovary and unites with it, thus fertilizing it anil 

 permitting it to grow intf) a pumpkin seed. Photograpli mucli enlarged. (Fig. 9.) 



he says are dissoh'cd just Vicfore fertil- 

 ization, and then just after fertilization, 

 to quote (1877): 



"The male nucleus Jormcd from the 

 contents of the pollen tube is found now 

 near the end of the tube, now near, or 

 in contact with, the ejj;g nucleus. . . . 

 The protoplasmic contents of the pollen 

 tube, I hold, jjasses throuj^h the (imi)er- 

 forate) tul)e-meml)rane in a diosmolic 

 manner." 



The fertilization of the j^ymnos])enns, 

 because of their lar^e ej.,'^s, ])ollen tubes 

 and mielci, was at this time bcinj^' st tidied 



by a number of workers. One of these, 

 Cjoroschankin, in 1<S83, was aljle to 

 demonstrate that in Finns pnmilio the 

 pollen tube opens at the end, and that 

 throujijh this ]jore the two male cells 

 l)ass bodily into the q^^. Goroschan- 

 kin's mistake, in su|)])osinj^ both male 

 nuclei to fuse with the e^j^ nucleus, was 

 corrected by Strasburj^er the followinji 

 N'ear. The latter (1884) .saw the same 

 i)odily exit of both male nuclei from the 

 open ]j()llen tube of Picea, Imt found only 

 one tnaie nucleus fusinj.; with that of the 

 v^^. Ill the same pubHeation Stras- 



