MEMORANDA. 295 
permits the separation of the two products, for on the prostate 
side of the uterine tube is situated a groove or gutter extend- 
ing its whole length, separated from the main cavity by a 
longitudinal valve-like structure, which allows the two canals 
thus formed to communicate with each other along its free 
edge ; this groove runs directly into the vas deferens, and thus 
conveys the zoosperms into the penis, from which their trans- 
ference into the spermatheca appears easy. I find that Dr. 
Lawson has not described this twofold structure of the cavity 
of the uterus, or rather, denies it ; but I found it easily enough, 
and it is well described by H. Nickel in ‘ Miiller’s Archives’ 
for 1844. As to the prostate being the largest gland of the 
whole apparatus, I should hardly think that that alone 
would be sufficient to substantiate its claim to the character 
of testis. Besides the above considerations in favour of the 
hermaphrodite character of the ovary, there are a few others, 
such as, if this gland does not secrete the zoosperms, how 
could they get there? Its duct is strongly ciliated, and the 
direction of the ciliary current is towards the outlet, and one 
would suppose that they would find great difficulty in making 
way against the stream, and in an immature condition it 
would be still more trying. 
In opposition to the above facts, Dr. Lawson has only to 
put forward the size of the prostate and a few “ oval and ellip- 
tical, cpithelial-like cells, usually described as the parents of 
zoosperms.”” 
I will leave it to your readers to say which view is most 
likely to be correct, and which looks more like a petitio 
principti.—Atrrup Sanpers, F.L.S., Brixton. 
The Theory of Circulation in the Vorticellide.—I have seen 
the contractile vesicle of Vorticellidee to present the follow- 
ing appearance under the microscope in the majority of 
cases : 
First. On certain movements of the reflector the vesicle 
entirely disappeared, but that on subsequent alterations of 
the position of the reflector I observed its reappearance. I 
am inclined to think that any subsequent contraction-like 
appearanee of the vesicle was due to the fact of its having 
been removed from the line of focus by the movements of the 
living animal; to the same cause I also attribute an expansion- 
like appearance of the vesicle. Hence the characteristic term 
“ contractile vesicle ”’ is inappropriate, unreasonabie, and un- 
founded ; the plain word vesicle being truthful. 
Secondly. I have never witnessed the processes proceeding 
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