.10 THE ROTIFERA. 



success, and lias lately bad thousands of Steplianoceros, Melicerta, Pterodina, &c, 

 thriving in tanks and jars in his study. Mr. J. Hood has been equally auccessful with 

 FlosciUaria and Limnius ; and I know of other instances in which a literally constant 

 stock of the tube-making Rotifera has been maintained in these home preserves. 



Indeed, if nothing more is desired than to watch the growth of a couple of generations 

 or so, an ordinary zoophyte trough is aquarium enough. All that is necessary is, (1) to 

 take great care that there are not many animals of any kind in it, (2) to keep it in a 

 subdued light, (3 1 and at a moderate temperature, (4) and especially to provide the 

 Rotifera with plenty of their natural food. For, in the great majority of cases, Rotifera 

 die when in captivity, of starvation : one moment's examination of their stomachs will 

 make that point clear. 



Of course, what is their natural food must first be observed under the microscope, 

 and then it must be provided to them every day by dropping a fresh supply of water 

 containing it into the trough. It will, therefore, always be necessary to bring away 

 from the pond, where they were found, a good supply of pond water free from all other 

 kinds of animals. 



Sometimes, however, it is well to make an overfed Rotiferon starve a little, in order to 

 see its internal structure. Hydatina scnta, for instance, is frequently so gorged with dark 

 green food, that little else can be seen but its distended stomach ; the organization of 

 Pedal ion mi rani, too, is often a hopeless riddle, owing to its greedy habits ; but drop 

 either of these creatures into a tube of clear soft water for an hour or so, and it may be 

 fetched out again in delightful condition for microscopic investigation, and yet perfectly 

 healthy. 



Summing up the various habitats that I have just recorded, we see that Rotifera 

 may be found in rivers, lakes, reservoirs, ponds, ditches, puddles, gutters, and water- 

 butts ; in the mud of dried ponds, in the dust of dried house-gutters, on wet moss and 

 grass ; in the rolled-up leaves of liver-worts, in the cells of Volvox globator and of 

 Vaucheria, in vegetable infusions ; on the backs of Entomostraca, and of fresh-water 

 fleas, wood-lice, shrimps, and worms ; in the viscera of slugs, earth-worms, and Naiades, 

 and in the body-cavities of Synapta. Nor have I yet completed the list ; for several 

 species have been found in the sea. Mr. Gosse says, 1 " Synehceta Baltica swims at large 

 through the water, never resting ; it is self-luminous, and is one of the causes of the 

 phosphorence of the sea. Brachionus Miilleri and Pterodina clypeata occur in brackish 

 water at the mouths of rivers ; and other marine species may often be detected by searching 

 with a pocket-lens the glass sides of a well-stocked aquarium." 



Since then these creatures have so wide a range of habitats, it is hardly possible 

 for anyone, who will take the trouble, not to find some of them near his own home. 



To obtain some particular Rotiferon, at a particular given time, is often difficult 

 enough, if not impossible ; but for one who is content to study these beautiful creatures 

 as he finds them, there is always a never-ending supply of delightful amusement. 



1 Marine Zoology, part i. 1855, p. 107. See also Tenby, 185G, p. 274. 



