96 MAINE AGRICULTURAL EXPERIMENT STATION. 1904. 



place which has resulted in some chemical differentiation. If 

 this theory is tenable, fusion is prohibited because the chemical 

 stimulus which unites the elements is impaired or destroyed. 

 Some slight change in the chemical composition of the gametes 

 or of the embryo-sac, perhaps both, would disturb the equi- 

 librium and impair the forces which cause fusion. As it now 

 appears, the egg-cell of crookneck is indisposed toward pollen 

 spores of golden custard, that is, there is a manifest expression 

 of selection with crookneck pistils. Not all pollen is congenial, 

 some pollen spores will not be received, and among these non- 

 receptive gametes are to be included those of golden custard. In 

 other words, this is apparently an example of what has been 

 called "sexual elective affinity." 



(3.) Some products of the crosses. 



When the fruits mentioned above had come to full maturity 

 they were cut open and in some cases many seeds were found 

 which appeared to be well formed. Such results were surpris- 

 ing, but were not to be accepted as demonstrations that these 

 reciprocal crosses can be made, until the fertility of the seeds had 

 been determined and the character of the offspring observed. 



The seeds were dried and planted to determine if they were 

 viable ; and if so, to ascertain if the offspring were also fertile. 

 The seeds were planted in the greenhouse, and the following is 

 the record of their germination. 



No. Of 



No. 



of seed 



No. of seeds 



No 



. of seeds 



Per cent 



the fruit. 



produced. 



planted. 



germinated. 



germinated. 



I 





195 



25 





5 



20 



2 





l6o 



25 









O 



3 





33 



25 





5 



20 



4 





40 



25 





5 



20 



5 





37 



25 





15 



60 



6 





56 



25 





14 



56 



The higher percentage of germination in the last two cases 

 may be accounted for by the more careful selection of seed ; only 

 the best were planted. The above figures are of value in show- 

 ing the degree of viability of the seeds. 



Bringing forward the figures previously used we have the 

 following statement : Of 284 pollinations more than 200 pistils 

 were left on the vines as long as they remained intact. From 



