Characteristics of Rotifers. 295 



I can only very briefly advert to the reproductive apparatus 

 of rotifers. It lias already been mentioned that the males of 

 those species in which they have been discovered (about 

 thirteen or fourteen) have but a brief existence. Mr. Gosse 

 — to whom we owe most of our knowledge of them — could 

 never preserve one alive for more than twenty- four hours. 

 They are unlike the females in appearance,, as well as in the 

 absence of digestive organs, and they contain patches of 

 opaque matter, which is white by reflected, and black by 

 transmitted light. Mr. Gosse was so fortunate as to see- one 

 emerge from an egg of Br a chionus palco, and was struck with its 

 differing from the ordinary offspring of that creature. 



The ovary of the female rotifer is remarkably conspicuous 

 and of peculiar shape in Asplanchna, looking like a long cushion, 

 bent in a more or less horse-shoe form. In the Plate, Fig. 1, 

 the ovary is shown, and Fig. 3 is a portion of it magnified 1000 

 times linear, showing the germinal vesicles from which the eggs 

 arise. In Asplanchna the internal apparatus has plenty of room, 

 and is extremely moveable. When everything is in its usual posi- 

 tion, the large stomach is seen hanging to the gullet, while the 

 ovary bends like a horse-shoe, and partially surrounds it. 



The nervous system of rotifers is probably simple, but as 

 yet imperfectly made out. In Brachionus a large cerebral 

 ganglion is seen easily behind the beautiful red eye; and in 

 Lacinularia, Prof. Huxley describes a "bilobed homogeneous 

 mass, resembling in appearance the ganglion of Brachionus, 

 and running into prolongations below ; but whether continued 

 into cords or not he could not make out/'' 



Many rotifers exhibit some symptoms of intelligence, as 

 when the common rotifer goes groping about, or the tube- 

 dwellers incline their heads towards particular objects. The 

 Metopidia acuminata has a curved organ like half a pickaxe 

 attached to its head, and works about with this, raking 

 amongst rubbish, and selecting what it requires, somewhat 

 like a French chiffonier with his hooked stick. If a number of 

 Brachions are put in a vessel they soon come near each other, 

 perhaps deriving some pleasure or advantage from the action 

 of each other's whirlpools ; but we must beware lest we 

 ascribe too much purpose to movements which may be the 

 involuntary results of circumstances, and it is curious that 

 Mr. Gosse observed a Melicerta making and depositing her 

 pellets, when her tube was broken, and she could place none 

 where they could be of use. 



The localities in which rotifers are found are chiefly in 

 fresh and salt water, though some can live in damp moss. 

 Some attach themselves to plants, others swim freely, and 

 others lurk in sedimentary deposits. I have found the 



