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W. M. Wheeler 
these bodies woiüd probably have long been regarded as problematic 
or rudiDiental. For bave not the true testes of the Oligochaeta been 
similarly overlooked and this term repeatedly and even recently 
applied to tbe vesiculae seminales? 
Moreover, as I bave sliown, tlie ovaries develop and grow tili 
tbe Myzostome bas reacbed its full size and tbencefortb sbow no 
signs of tbe diminution commonly seen in rudimental or vestigial 
structures. 
Tbe small size of tbe cells cannot be taken as an indication of 
a rudimental condition of tbe organ, since nearly all tbe tissues of 
tbe Myzostome consist of very small cells. Tbe karyokinetic figures 
so offen found in tbe ovarian cells long after tbey bave disappeared 
from tbe otber tissues and in relatively late stages of tbe animal's 
growtb, flatly contradict Nansen’s and Beakd’s supposition. 
Tben, too, Beard must know tbat it is always more difficult 
to prove tbat an organ does not tban tbat it does function. In tbis 
case also tbe bürden of proof lies witb bim wbo denies. 
In bis baste to point out tbat my interpretation is inadequate 
Beard appears to bave lost sigbt of tbe fact tbat be bas never yet 
sbown tbat tbe general peritoneal epitbelium of Myzostoma may 
give rise to ova; and tbat in tbe absence of figures bis assertions 
could not pretend to any greater weigbt tban tbose wbicb I advanced 
in my preliminary paper. 
8) Beard makes the Statement (pag. 403) : »Many of the extreme 
cysticolous forms bave been sbown to be dioecious.« Where bas 
this been sbown? Certainly v. Grafe, wbo bas given us almost 
tbe only observations wbicb we possess on tbe Cysticola bas never 
»sbown« tbis. All of tbe so-called dioecious Cysticola described by 
V. Graff are quite as readily interpreted as protandric and hystero- 
gynous bermapbrodites. 
9) Beard’s Insinuation tbat my prediction concerning M. puhinar 
was only made »to bolster up an argument wbicb is otherwise un- 
tenable« calls for no comment after what I have said of this species 
in the present paper. 
In a Lumhricus terrestris 170 mm long, the ovaries were only 1.25 mm long, 
and in a specimen of Allolohophora foetida 100 mm long, the ovaries clid not 
exceed 1 mm in length. In a M. glahrwn measiiring 3 mm in length, each of 
the ovaries measured ahout 0.1 mm, so that the length of the ovaries of the 
Myzostome compared with the length of the body is more than 30 times as large 
as those of the earthworm. 
