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MR. J. DALRYMPLE’S DESCRIPTION OF AN INFUSORY 
It may be stated, in limine, that it is now certain that these animals are divided 
into female and male, the latter being one of the most curious organisms I am ac- 
quainted with. 
As however the general description has hitherto been taken from the female, I shall 
describe the reproductive organs in them first. 
There is an ovary, ovisac, expulsory mechanism, vaginal canal and vulva. 
The ovary (Plate XXXIII. fig. 1 O) consists of an elongated mass, curved into the 
general form of a horseshoe, either extremity being rounded and slightly enlarged. In 
texture it appears gelatinous, with numerous interspersed granules, forming a stroma, 
in which are imbedded many nucleated cells (Plate XXXIII. fig. 1) that afterwards 
become ova. The ovary is larger in proportion as the animal is young, and visibly 
shrinks and becomes almost atrophied as it is advanced in age and has produced 
many embryos. This ovary, like the stomach, is very moveable in the general cavity 
of the body, but in the newly-born female, before many movements have taken place, 
and especially before the stomach has been distended with food, its position is such 
that the two horns are pointed upwards, and the digestive sac is placed within the 
concavity of the horseshoe (Plate XXXIII. fig. 2 0 0): thus the ovary is symmetrically 
placed, and appears like a double organ united by a broad bridge in the centre. To 
either horn are attached slender muscles or tegumentary fibres that retain it in its 
general position, although either producing or permitting free movements ; for when 
the ovisac becomes distended with one or more embryos, which always occupy the 
lower part of the animal, it, as well as the stomach, is pushed out of its ordinary or 
original position. 
To the lower part of the ovary appears, connected by slight muscular or ligament- 
ous fasciculi, the extremity of the ovisac, which, if unoccupied by an embryo, is closely 
contracted, and appears like a wavy, extremely delicate membrane. The female is 
both oviparous and ovo-viviparous, the latter condition being the one most frequently 
observed ; and in fine hot weather it is not unusual to find females with four or five 
young in various stages of development, from the early ovum to the mature embryo, 
ready for expulsion. 
The extreme transparency of the animal permits the ready observation of all stages 
of development. We can trace the germinal vesicle, surrounded by a gelatinous and 
granular mass or yelk, and enveloped in a delicate chorion, still attached to the ovary. 
The germinal vesicle is generally very distinct and excentric (Plate XXXIV. fig. 2), the 
whole egg being an ovoid figure. The ovum is then enveloped by the open end of the 
ovisac, and the base of attachment to the ovary being gradually narrowed to a small 
peduncle, it finally escapes free into the membranous ovisac, where the further develop- 
ment is carried on. We then shortly observe the ovum to increase in size, the distinct 
and dark granulesappearing to become surrounded with cell -walls, and the gelatinous 
mass is converted into a large number of distinct nucleated cells, Plate XXXIV. fig. 3. 
I cannot say I have traced the division of the original cell into two, four, eight, &c. in 
