90 MAINE AGRICULTURAL EXPERIMENT STATION. I904. 



The pistil of the yellow plum, on the other hand, is continuous 

 with the tissue of the ovary and does not exhibit that narrowed 

 structure which is seen in the red currant; but, in fact, is larger 

 and broader there than elsewhere. 



This comparison brings up the mechanical feature in crossing 

 these two species. Here, then, one may note that the red cur- 

 rant flowers can be successfully emasculated only by exercising 

 great care, on account of the ease with which the style separates 

 from the ovary, a slight push to one side being sufficient 

 to detach it. Furthermore the pistil is very slender and exceed- 

 ingly delicate, and being deprived of the protection which the 

 united stamens afford, it is exposed to changes of temperature 

 and moisture which in most cases are fatal to the pistil. 



In successful emasculation of red currant, and with the ordi- 

 nary method of covering the flowers with paper bags, it was 

 practically impossible to keep the pistils fresh till the period of 

 receptivity. In the majority of cases the pistils withered in the 

 course of twenty-four hours after emasculation, and hardly a 

 single one could be found in perfect condition three days after 

 the removal of stamens. Even when the pistils did survive and 

 were pollinated they did not remain fresh long enough for the 

 pollen to do its work. 



In view of these difficulties, it became evident that some means 

 should be provided to prevent the withering and dying out of the 

 pistils. Instead of covering each cluster of flowers with manilla 

 bags, glass bell-jars which covered the whole plant were used., 

 thus eliminating to a marked degree the exposure of the pistils, 

 and securing a fairly uniform condition of moisture and tem- 

 perature. It should be said here that this scheme was feasible 

 only by using small plants and very large glass bell-jars. By thus 

 protecting the flowers, and in fact the whole plant, less difficulty 

 was experienced in keeping pistils in good condition as long as 

 seemed necessary. Nearly as good results were obtained by 

 using double paper bags, and similarly covering the whole plant. 

 Such good results followed these special methods that the real 

 difficulty in making these reciprocal crosses was considered to 

 be mechanical, and this difficulty can be very largely overcome 

 as previously indicated. 



Seeds saved from fruits of these reciprocal crosses, produced 

 fertile plants, and thus we have an answer to our opening ques- 



