New York Agricultural Experiment Station. 519 



gree of self-fertility which they have shown in these tests, into 

 four lists which are given in full in the body of the report. Class 1 

 includes self-fertile varieties having perfect clusters or clusters 

 varying from perfect to somewhat loose. Class 2 includes self- 

 fertile varieties having clusters loose but marketable. Class 3 in- 

 cludes varieties which are so imperfectly self-fertile that the self- 

 fertilized clusters are generally too loose to be marketable. Class 4 

 includes the self-sterile varieties. Whenever cross-pollination has 

 been prevented these have developed no fruit. 



The varieties named in Classes 1 and 2 form marketable clus- 

 ters from self -pollinated blossoms and may be planted alone. Those 

 which are named in Classes 3 and 4 should be planted near other 

 varieties which bloom at the same time because when cross-polli- 

 nation is prevented they either produce no fruit or the clusters 

 which develop are too loose to be marketable. Lists showing the 

 period of blooming of most of these varieties are given in this 

 report. 



The method of testing grapes as to self -fertility by covering the 

 clusters during the blooming season to prevent cross-pollination is 

 certainly reliable with varieties which have long stamens, and 

 apparently so with all other varieties. 



Short or recurved stamens are always found associated with 

 complete or nearly complete self-sterility. 



Long stamens are not a sure indication of self-fertility because 

 some varieties which have long stamens are self-sterile. 



The most satisfactory explanation of the self-sterility which 

 exists among grapes appears to be that there is a lack of affinity, in 

 the self-sterile varieties, between the pollen and the pistils of the 

 same variety. 



HISTORY OF INVESTIGATIONS. 



Investigations concerning the self-fertility of grapes were begun 

 at this Station in 1892 and the work has been continued till 

 the present time. These tests have included twelve American 

 species, together with many of their hybrids with each, other and 



