70 On the Paramecium aurelia. 
Art. XII.—On the Paramecium aurelia; by Ocpen Roop, A.B. 
[Read before the Berzelian Society of Yale College, Nov. 30.] 
vine accidentally produced a large crop of the Paramecinm 
aurelia in an infusion of hay, I was tempted from their very 
abundance to make some observations. One of the most re- 
markable features of this animalcule is the possession of two 
or more star-like contractile vesicles. Ehrenberg, according to 
Pritchard, ‘considers the rays of the star-like vesicle as a ductus 
spermatici, which is long and enters the ovarium at many points.” 
It will be seen by an attentive examination 
that the said duct discharges into, and not from, 
the vesicle a quantity a liguid which distends 
and fills it in about a minute, when the vesicle 
contracts ejecting the laid from the body by a 
small opening: then the ducts empty into the 
vesicle their immediate contents and afterwards 
from water ; the most natural conclusion then 
is that it is water. On placing a number of 
these animalcules in water mixed with indigo 
1g 
and compressing the drop so that they shall be held nearly star 
tionary, but by no means crushed, the action is apparent; the 
indigo with the water is seen to enter by the mouth near the 
middle of the body, and at the bottom of the mouth the pigment 
is rolled around till it forms a ball: meanwhile the ducts are seet 
to distend conveying the water from the mouth into the respect 
ive cavities. If this view of the matter be correct, the P. aurelia 
is not, as was formerly supposed, possessed of male organs. I 
have not been able, except in two or three doubtful cases, to trace 
“ ducts completely to the mouth. The vesicles with the duets 
situated near the surface and immediately under the investing 
reidaiioceae being thus out of the way of foreign bodies intro- 
duced into the interior of the animalcule. It is to be remar 
that the cavity into which the ducts empty is not one fortuitously 
formed in the mobile substance of the body, but is lined with @ 
distinct membrane. This can be observed by cautiously erush- 
ing an individual so as merely to rupture the integument, whet 
the contents peur out: the vesicle with the water contained in it 
will then pass out without breaking up and mixing with the 
surrounding particles, The action of the cilia Rsroanans the 
body would seem to be involuntary, for when the body is 
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Ren Ma Ss 
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