904] LYON: EVOLUTION OF THE SEX ORGANS 281 
In the course of conducting university classes in general mor- 
dhology for the past few years, I have had occasion to examine 
Many preparations of representative plants of the chief groups, 
and have become impressed by the comparative frequency of 
Certain irregularities in the development of the sex organs, par- 
icularly in pteridophytes, that show their plasticity and are sug- 
‘gestive from the evolutionary standpoint. I am inclined to look 
‘upon the “monstrosities,” as biologists are fond of calling organ- 
1s which do not conform to a morphological rule of thumb, as 
resenting hints of ancestral conditions which afford at least a 
ogical theory of the origin of the sex organs. 
In a recent paper on the “Origin of the archegonium,” Davis 
(1) has given a series of diagrams of hypothetical transitional 
forms to illustrate his view of the evolution of the sex organs 
from a plurilocular sporangium similar to that of Ectocarpus vires- 
eens. His theory would be far more convincing had he cited 
actual rather than hypothetical transitional forms, and such evi- 
dence.is not difficult to obtain. 
In an article on the development of the archegonium of 
‘mosses, Hy (2) describes an organ of mixed sexual character 
which has the egg apparatus at its base, and is distinctly sperma- 
togenous atthe summit. This phenomenon, he says, is not uncom- 
mon, occurring in several species— notably in Atrichum undulatum. 
~ Unfortunately he gives no figures of this interesting variation. 
Many instances of a similar nature in Mnium cuspidatum were 
observed by students in the Hull Botanical Laboratory two years 
go, and figures of bisexual organs from this material appeared 
in Holferty’s (3) paper in the February number of the BoranrcaL 
7AZETTE. None of the plants in that collection was mature 
enough to determine the future of the gametes, or whether the 
Sperms were actually formed.’ That the tissue appearing in a 
Single organ consisted of immature cells of two kinds there can 
no doubt. That antheridium and archegonium are homolo- 
ous organs is a logical conclusion from the fact that cells at 
the apex of a moss shoot may indifferently develop into male, 
*Since the above was written, specimens have been secured with perfectly 
typical moss sperms which were discharged from the antheridial region above the egg. 
