POLLEN AND PISTILS OF APPLES 403 



wash away or dilute the stigmatic secretions and thereby pre- 

 vent the setting of fruit. 



It has also been stated that freezing temperatures kiE the 

 stigmas which consequently do not function properly and as a 

 result pollination is not effective on the stigma. This point was 

 investigated, but to a very limited extent. Clusters of flowers 

 were exposed to freezing temperatures until the styles were 

 killed. The flowers were then removed to a temperature of 

 about 25° C. and their stigmas pollinated with pollen that had 

 been at room temperature. On the stigmas of these dead styles 

 very good germination of the pollen was obtained. 



THE STYLE. 



The style is grooved just below the stigma, the groove being 

 almost a millimeter in length. In this region there are many 

 small vascular strands which reach to the base of the stigma and 

 within a few cells of the papilla. The outer walls of the epi- 

 dermal cells are cutinized. When stained with safranin the line 

 separating the papillge of the stigma and the epidermis of the 

 style is quite distinct. Tests for sugar at the tmie of pollination 

 with phenylhydrazine hydrochloride and sodium acetate gave 

 the results shown in table VII. 



Table vii 



In some cases in the same flower, some styles showed abund- 

 ance of cane sugar while others showed none. In Gano there 

 was much more cane sugar in the styles before the fljwers 

 opened than at pollination. The sugar when present was found 

 abundant in the sieve vessels. 



