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W. M. Wheeler 
liaving lost its male Organs, tbe male tlie female Organs which it 
originally possessed. The opposite view, viz. that hermaphroditism . 
is a secondary condition brongbt about by tbe acqnisition of tbe 
Organs of tbe opposite sex in animals originally dioecious or gono- 
cboristic, bas been advocated by Beard {'84), Fritz Müller ('85) 
and Delage ('84), and more recently by Pelseneer {'94) and Mont- 
GOMERY ('95). To tbese investigators, especially to Beard and 
Fritz Müller, tbe Myzostomes appeared to be very important, since 
they were snpposed to present tbe transitions from gonochoristic to 
bermapbrodite forms tbrougb species witb »complemental males^c. 
Tbese last were naturally supposed to represent tbe evanescent 
rndiments of a sex wbose essential organs had been, so to speak, 
grafted on to tbe reprodnctive organs of tbe female individual. In 
species like M. cirriferum tbe male individuals were supposed to 
bave been completely eliminated. 
Nansen’s objections to tbis view ('85, pag. 79 and 80), together 
witb tbe facts recorded in tbe present paper, show clearly tbat tbe 
Myzostomes can no longer be used as evidence of tbe derived nature 
of bermapbroditism. I do not by any means believe tbat tbis with- 
drawal of tbe Myzostomes is a death-blow to tbe general hypothesis 
of Beard and Fritz Müller; on tbe contrary, tbe evidence still i 
remaining, especially that contained in tbe latter autbor’s paper and 
in Pelseneer’s interesting contribution, bas considerable weight and 
is calculated to sbake our faitb in tbe older and wider spread 
doctrine of tbe pbylogenetic derivation of gonochorism from berma- 
pbroditism k 
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 seeins to me, is in urgent need of thorough and critical 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 reproductive 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- 
