REPORT ON TESTS OF SELF-STERILITY IN PLUMS, 

 CHERRIES, AND APPLES AT THE JOHN INNES 

 HORTICULTURAL INSTITUTION. 



Prepared by IDA SUTTON, 



Student in the Institution. 

 (With Plate XV.) 



The work to which this report relates was begun in 1911 by 

 Mr W. 0. Backhouse and Mr M. B. Crane. It has been continued in 

 each succeeding year, and among others who took part in it must be 

 mentioned Lt. Sherrard, Prof. Kusano, Prof. Chibber, and Miss Garlick. 

 My responsibility in connexion with the observations began in 1915. 



Preliminary reports on the eai'lier stages of the work were made by 

 Backhouse (1, 2, 3). It is greatly to be regi-etted that this report had 

 to be prepared without consultation with those who preceded me in 

 the work, most of whom are absent on foreign service. 



The objects were in part economic, for since the work of Waite and 

 others it has been recognized that failure of fruit crops is not unfre- 

 quently due to self-sterility ; and in addition it was expected that the 

 work might elucidate the physiological nature of this phenomenon. At 

 the jjresent stage no comprehensive discussion of the genetic problems 

 can be offered. In view of the recent experiments of others two main 

 questions arise, (1) whether self-sterility is a simple Mendelian recessive 

 character; (2) whether the older observers were right in considering 

 that in such cases self-steriles are fertile with the pollen of any other 

 variety, or whether there are not, rather, several classes of individuals, 

 between which there is what East has called " Cross-incompatibility." 

 As regards the first question there is nothing in our results which 

 negatives the view that the jjroperty of self-sterility maybe a recessive, 

 but until a later generation can be tested, the only evidence bearing on 

 this aspect of the matter is the fact that the results with plums and 

 cherries are consistent with the supposition that the plants consist of 

 two larger classes, self-fertiles and self-steriles, with a smaller number 

 of plants of intermediate properties. These and presumably some of 

 the self-fertiles may be supposed to be heterozygous. The self-sterile 

 class forms a fairly homogeneous group, and the occasional indications 



