292 
W. M. Wheeler 
having lost its male organs, the male the female organs which it 
originally possessed. The opposite view, viz. that hermaphroditism 
is a secondary condition brought about by the acqiiisition of the 
Organs of the opposite sex in animals originally dioecious or gono- 
choristic, has been advocated by Beard ('84), Fritz Müller ('85) 
and Delage ('84), and more recently by Pelseneer ('94) and Mont- 
<>OMERY ('95). To these investigators, especially to Beard and 
Fritz Müller, the Myzostomes appeared to be very important, since 
they were supposed to present the transitions from gonochoristic to 
hermaphrodite forms through species with »complemental males'f. 
These last were naturally supposed to represent the evanescent 
rudiments of a sex whose essential organs had been, so to speak, 
grafted on to the reproduetive organs of the female individuai. In 
species like M. cirriferum the male individuals were supposed to / 
have been completely elimi nated. 
Nansen's objeetions to this view ('85, pag. 79 and 80), together 
with the facts recorded in the present paper, show clearly that the 
Myzostomes can no longer be used as evidence of the derived nature 
of hermaphroditism. I do not by any means believe that this with- 
drawal of the Myzostomes is a death-blow to the general hypothesis 
of Beard and Fritz Müller; on the eontrary, the evidence still 
remaining, especially that contained in the latter author's paper and 
in Pelseneer's interesting contributioü, has considerable weight and 
is calculated to shake our faith in the older and wider spread 
doctrine of the phylogenetic derivation of gonochorism from herma- 
phroditism i. 
1 The advocates of this older view have always laid considerable stress 
on the hermaphrodite characters of the embryos of gonochoristic animals. This 
subject, it seems to me, is in urgent need of thoroiigh and criticai reinvesti- 
gation. The facts themselves are far from being satisfactorily established, and 
the use of terms is often very loose and unscientific. To give only two in- 
stances: the stage of sexual neutrality or indifference in the embryos of gono- 
choristic animals is often called hermaphrodite. But we are not justified in 
using this term to describe the undifferentiated sexual Anlage which may be 
converted under certain conditions, as yet very imperfectly known, into a male 
and under other conditions into the female reproduetive organ. This is per- 
haps as great an absurdity as to say that water is a compound of ice and vapor, 
because the liquid is convertible under certain fixed and well known conditions 
into a solid, and under other conditions quite as definite, into a gas. Watase 
('92), too, has called attention to this error. 
Then again, several authors, confounding sex and heredity, speak of the 
cleavage cells of the egg and even of the cells of the adult organism as herma- 
