i 9 o8] GATES— REDUCTION IN OENOTHERA 27 



pairs, whether from an end-to- end or side-by-side union of somatic 

 chromosomes, or in any other manner, so that this question holds no 

 necessary relation to the method of reduction. On the common 

 cytological assumption that the chromosomes are qualitatively 

 different (which has apparently been shown to be a fact in certain 

 well-known cases in animals, that need not be cited), germ cells 

 would occasionally arise lacking both members of a pair, and hence 

 lacking the possibility of developing certain qualities. In this manner 

 it is conceivable that a series of types might arise from the parent 

 O. Lamarckiana, each lacking the possibility of developing a certain 

 group of characters possessed by O. Lamarckiana. 



On this view, which is suggested merely as a tentative hypothesis, 

 we would have in the mutations of O. Lamarckiana an analytical 

 process in which a series of types arises from the parent form, each 

 lacking in a different group of qualities or capacities which the parent 

 form possessed. This does not apply to O. gigas, however, which will 

 be taken up at another time. The further bearings of this hypothesis 

 on the mutation theory of DeVries will not be followed up in this 

 discussion, but it may be pointed out here that such a hypothesis 

 accounts for the absence of reversions of the mutants to O. Lamarcki- 

 ana, and it may also account for some of the peculiarities of 

 hybridization among the Oenothera mutants. I should therefore sug- 

 gest that there may be a relation between the type of reduction in any 

 organism and its variation and hybridization phenomena. 



In Galtonia and probably also in Tradescantia there are apparently 

 the same possibilities that both chromosomes of a pair may occasion- 

 ally enter the same daughter nucleus. In other plant forms studied 

 the attraction between chromosomes seems to be strong enough to 

 keep the members of a pair together until their separation in the 

 anaphase of the heterotypic mitosis. The segregation of the members 

 of a pair into separate germ cells is thus insured. In cases where, 

 as in Oenothera, the members of a pair do not always remain in 

 contact, but are loosely arranged on the spindle, such a result as 

 already suggested seems certain to occur in certain instances. 



It has already been mentioned that occasionally one chromosome 

 goes to the wrong pole of the heterotypic spindle. This is found to 

 be the case particularly in the hybrids, for example, in the O. Lamarcki- 



