No. 374.] PLANT MORPHOLOGY AND PHYSIOLOGY. 103 
periclinal divisions in the regions mentioned. The definitive arche- 
sporium is formed by not more than a single anticlinal division of 
the primitive archesporial cells. : 
The macrosporic archesporium apparently develops no primary 
tapetum, divides simultaneously from the two-celled stage, and the 
third or fourth cell becomes the definitive embryo sac mother cell. 
The archesporial nucleus, especially, is peculiar in the large 
nucleolar-like structure, which is evidently not homogeneous in 
structure, a portion of it taking the gentian in the Flemming 
combination, 
WALTER T. SWINGLE: Some Theories of Heredity and of the Origin 
of Species Considered in Relation to the Phenomena of Hybridization. 
Owing to limited time, the speaker treated only the first portion of 
his theme, zz., the bearing of the facts of hybridization on some 
theories of heredity. It was pointed out that Weismann’s theory of 
reduction of chromosomes, though giving a plausible explanation 
of the differences observed between the first (uniform) and second 
(polymorphic) generations of most hybrids, is not in accord with the 
observed phenomena of spore and pollen formation in higher plants, 
and, moreover, fails to account for the extreme polymorphism often 
observed in the first generation of hybrids of races of cultivated 
plants or closely related species, as, for example, some racial hybrids 
of maize and some specific hybrids of Lychnis and Digitalis. Mr. 
Swingle considered it necessary to assume in some such cases, at 
least, a predetermination of the characters of the hybrid at the time 
of fusion of the male and female nuclei. 
Since the male and female chromosomes probably persist side by 
side unchanged in number, and possibly unchanged in quality during 
the whole of the ontogeny of the hybrid (reduction not occurring 
until the close of the first generation), it is therefore necessary to 
assume, in order to explain the observed fact of divergence of char- 
acter in the first generation of some hybrids, that the influence 
exerted during ontogeny of the hybrid by the material bearers of 
heredity is, at least in some cases, a function of their relative posi- 
tions, and, further, that in most cases the relative positions of these 
bearers of heredity, as determined at the moment of fusion of the 
male and female nuclei, would persist unchanged throughout ontogeny 
of the offspring. Some exceptional cases, such as reversions to the 
one or the other parent form of a larger or smaller part of the hybrid, 
would be explained by assuming some change in the disposition of 
the units of hereditary substance, whereby they assumed a new posi- 
