The Sexual Phases of Myzostoma. 
265 
The same holds good also of the »lateral oviducts« of Nansen, or 
nephridia, as I prefer to call them. It may be confidently put 
down as a fact that all the characters in which the so-called com- 
plemental males of M. glahrum and allied species differ from the 
hermaphrodites are simply the characters of younger individuals and 
not by any nieans necessarily or even probably those of another sex. 
4) One of Beard’s main objections is a curious bit of reasoning. 
At pag. 401 he says: »Wheeler is in error in his supposition that 
all the youngest specimens on the disc are larger than those seated 
on hermaphrodites. It is quite easy to find individuals on the disc 
of Antedon as small and smaller than the supposed males, and a 
comparison of the two, i. e. of very small hermaphrodites from the 
disc and of males from the backs of hermaphrodites has supplied 
evidence strongly supporting my form er conclusions.« 
For the purposes of comparison a series of males were taken 
and sectioned and a corresponding set of w^hat were presumably 
young hermaphrodites from the disc were treated in the same way, 
the size of the individual being estimated by the number of sections 
of a given thickness (Yns mm). Beard sectioned 8 males which 
»yielded 66, 70, 78, 79, 90, 97, 128 and 151 sections respectively, 
while the 12 hermaphrodites furnished 93, 94, 97, 97, 100, 112, 
138, 138, 140, 152, 160 and 168 sections«. 
And this is »evidence« that the males cannot be merely young 
hermaphrodites! Two perfectly patent errors in this »evidence« — an 
error in method and one in common sense — seem not to have revealed 
themselves to Beard. In the first place, does Beard imagine that 
during the fixing and embedding process all Myzostomes retain exactly 
the same size which they had in life, or contract in such a uniform 
manner as to make the counting of sections a reliable method of 
measurement ? Is he quite sure that he has overlooked no young ova 
in the body-cavity of the »males« from 97 — 151 sections in length? 
And then, in the second place, even granting that the two series 
may overlap — and I do this willingly, being quite at a loss to 
know where I ever »supposed« that »all the youngest specimens on 
the disc are larger than those seated on the hermaphrodites« — what 
has this overlapping to do with the question at issue? Obviously 
nothing at all, unless Beard wishes to maintain the absurdity 
that all the individuals of a given species of animal at the moment 
of reaching sexual maturity are convertible into exactly the same 
number of microtome sections of Yiis in thickness! The morpho- 
