412 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



The relation of incompatibilities giving sterility to cell organiza- 

 tion. — The particular types of cell organization which Correns 

 and East assume to be involved in the cause of sterility have 

 already been quite fully discussed. Quite a different view of the 

 influence of cell organization may be considered and from at least 

 two aspects. A particular type of somatic idioplasmic consti- 

 tution may be associated with the dc\clopment of self-sterility 

 in respect to the role of the nucleus, as a part of the whole, in the 

 nucleo-cytoplasmic relationships determining the activities of cells 

 and their intercellular relations in the individual organ or plant. 

 A particular type of diploid nucleus may also be of significance in 

 sterility through its influence on the diff^erentiation of sex organs 

 and of the gametes whose nuclei arise from them. In respect to 

 these points it is to be noted, as East has emphasized in respect to 

 the relations of the sporophytic style and gametophytic pollen 

 tube, that the causes of sterility from physiological incompati- 

 bility are operating in a plant itself largely independent of such 

 differences in the particular idioplasmic constitution of the sex 

 organs as may result from reduction divisions. 



Perhaps a better assumption which would provide for the 

 sporadic occurrence of the differences which must be assumed to 

 be responsible for self-sterility in the case of self-fertile offspring 

 from self-sterile parents or, vice versa, of self-sterile offspring from 

 self-fertile plants, in which latter process all self-sterility doubtless 

 originated, is that of new or differentiated cell organization re- 

 sulting from such processes as Swingle ('13) has called zygotaxis. 

 This is especially an emphasis of a new difterentiated condition 

 which may arise in the cytoplasm directly as a result of the rela- 

 tive distribution and position of the chromosomes in the nucleus. 

 We must recognize a large amount of evidence that chromosomes 

 have a fixed position in the nucleus as Boveri has so clearly shown 

 in A scar is. But sporadic changes in the arrangement of chromo- 

 somes such as are assumed in the hypothesis of zygotaxis may 

 well occur in nuclei where the number of chromosomes is larger, 

 and thus provide for new cytoplasmic conditions of the sort 

 which may be assumed to account for (he phenomena of self- 

 sterility. 



In TABLE 3, data are gi\-en for 5.S plants of (he cross A X E22: 

 in these Fi hybrids, from jKirenls which (iilTcrcd wideh', (lie reduc- 



