518 Royal Society. 
PROCEEDINGS OF LEARNED SOCIETIES. 
ROYAL SOCIETY. : ; 
Feb. 22, 1849 —Reada paper, entitled “ Descripti on éf an In aly 
Animalcule allied to the genus Notommata of Ehrenberg, } hitherto 
undescribed*.” By John Dalrymple, Esq., F.R.C.S. 
The examination of various specimens 0 of the animalcule described 
by the author, disclosed the dieecious character of one of the more 
highly organized of the rotiferous class of Infusoria, hitherto sup- 
posed to be androgenous. This discovery was first made by obser- 
ving the difference in the form and development of the embryo 
while still enclosed in the ovisac of the parent animal. From the 
extreme transparency of this form of rotifer, it is possible to trace 
the progressive development of the young from the Greffian vesicle 
in the ovary to the period of mature gestation, when the embryo is 
expelled, the whole machinery of whose organs has been perfected 
while still within the body of the female. 
Thus, although the young one observed in the ovisac, when nearly 
ready to be expelled, was in the great majority of instances a mi- 
niature portrait of the parent, yet occasionally an embryo was seen 
of a different aspect, within whose body a vesicle was, discovered 
filled with actively moving spermatozoa. 
A further investigation of the subject brought clear cnidetagial 
the functions performed by this male,—its copulation with the young 
females; but it also displayed the singular fact, that —_—a 
organs of reproduction and locomotion were highly developed, there 
was a total absence of those of assimilation; in fact, that neither 
mouth, nor stomach, nor other digestive cavity or glands, were pre-_ 
sent in its curious organization. 
In the early part of the paper the author describes the anatomy 
of the female, which differs from the family of Notommata of Ehren- 
berg, in the absence of intestine and anal orifice, and forcipated or 
caudal foot. In every other respect the organization is so similar to 
that class, that the author believes the proper place for this animal- 
cule to be in a sub-genus of Notommata. 
In relation to physiology, the author submits a new theory of the 
mechanism of circulation and respiration in the general group of 
Rotifers, a subject which is but obscurely treated of by the great 
German observer, who appears to have believed in the existence of 
tubular vessels or true vascular system. The author thinks, how- 
ever, that these functions are performed i in a manner more resem- 
bling that of insects, viz. that the blood is contained in the general 
cavity of the animal and circulates round the lung, which is here 
represented by a contractile vesicle that receives and expels. the 
water in which the animalcule lives, and so comes to be in mterme- 
diate relation with the air mixed with the water. The difference 
therefore between the aération of the blood of insects and that of this 
rotifer is rather due to the difference of the media they respectively 
inhabit, than of design. In both, the blood is contained in a general 
* [A paper on this subject by Mr. J. Brightwell, illustrated with a plate, 
appeared in the ‘ Annals’ for September 1848.—Ep. Ann. Nat. Hist.] 
‘ 
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