336 
MR. J. DALRYMPLE’S DESCRIPTION OF AN INFUSORY 
Besides this development of his views, it will be found that the great naturalist, in 
the explanation of the plate illustrating the anatomy of Hydatina Senta, believed the 
cords to whieh the gills or vibratory corpuscles are attaehed to be male organs, 
‘‘testiculi” {mannliche driisen) ; a position most unlikely for the location of respira- 
tory organs, w’ere they even probably such. As it will be proved that in the ani- 
malcule I am describing no such male organ exists under this form, and that another 
apparatus appears to subserve the office of respiration, it is far more probable that 
they are part of the mechanism of circulation, and, as such, secondary to the function 
of respiration. 
It has been previously stated that a valvular opening exists in the inferior part of 
the animal that gives exit to the matured embryo or to ova, and may therefore, from 
its obvious and demonstrable purpose, be denominated the vaginal aperture. This 
communicates with a membranous, highly extensible and very contractile ovisac 
(Plate XXXIII. fig. 1 P), in which the foetus is matured, and by the contractions of 
which it is finally expelled from the mother. 
Just above the ovisac, and communicating with the vaginal canal, is a considerable 
transparent sac (Plate XXXIII. fig. 1 N), which, when distended, presents a spherical 
shape. It is exceedingly delicate, and may be seen to contract by the action of slender 
muscular fibres with great rapidity, in which act it is thrown into numerous regular 
folds or pouches, and in that condition appears not very dissimilar to the large cellular 
lungs of Batrachia. These contractions and subsequent dilatations go on with some 
approach to regularity, and I have counted from six to eight in a minute ; but when the 
animal is disturbed, or attempting to escape from the pressure of the “ live cage,” or in 
the act of expelling an embryo, the contractions and dilatations of the sac are greatly 
and irregularly increased, sometimes to twenty in the minute. It is on the outside 
and over this sac that the principal ciliated tags of the circulatory organ are placed. 
The explanation which I venture to give is, that this sac draws in the water in which 
the animal lives, and expels it again by the vaginal orifice, and it is by bringing the 
blood by means of the ciliary movements of the little bodies just described into in- 
termediate contact with the air of the water, the fine membrane of the contractile sac 
alone intervening, that aeration or respiration is performed. An analogous contrac- 
tile sac may be seen in Rotifer vulgaris, situated near the cloacal orifice. 
At first sight this pulmonary sac (Plate XXXIII. fig. 7 C) appears to be an appendage 
to the ovisac (Plate XXXIII. fig.7 D),but frequent observation of the female in all stages 
of gestation convince me that it has no relation to the generative function. The same 
sac is described by Ehrenberg, in the explanation to the figure of Notommata Myr- 
meleo, as a contractile male vesicle with evident vascular ramification. The position 
and the description of a contractile bladder show that the learned Professor is speak- 
ing of the same organ I have described, but it will be clearly shown by and by that 
it has no concern with sex, while the vascular ramifications are neither more nor less 
than the muscular fibrillee by which the contractions are effected. 
