466 GENERAL HISTORY OF THE INFUSORIA. 



The Syncliceta Baltica has been presumed to be phosphorescent; and 

 Anurcea hiremis was discovered in phosphorescent sea-water. 



The Rotatoria are distributed everywhere over the surface of the earth, in- 

 habiting its waters, both fresh and salt. Of the known species, by far the 

 greater number are dwellers in fresh water, abounding in pools, ditches, and 

 gently-flowing streams, especially where aquatic plants grow in sufficient 

 quantity to afford shelter and indirectly suj)ply food by the hosts of animal- 

 cules which congregate on and about them. A too much overgrown or shaded 

 piece of water is less favourable ; for they require a complete intermixture 

 of air with the water, and the vivifying influence of the sun, for their healthy 

 existence. Some species especially delight in the little turfy pools on moors 

 or in boggy ground; others have been especially found in green-coloured 

 ponds — the colour being due to Protozoa and minute Algse, which furnish 

 them with suitable food. 



Some of the early observers sought these animalcules especially in infusions, 

 very generally made vrith sage-leaves and chopped hay ; but the E,otifera are 

 comparatively rare in infusions : a few common species only appear ; and unless 

 the infusion be comparatively fresh, none will be found ; for they occur in no 

 fluid in which decomposition is going forward. When they do exist in these 

 infusions, they appear at a later period than do the Monadina and less highly 

 organized infusorial forms. 



The known salt-water species are comparatively few ; this is very possibly 

 owing to their being much less sought after than the freshwater animals. 

 The principal marine forms recognized are Brachionus Millleri, B. he/ptatomus, 

 and Synchceta Baltica. Distemma marina and Furcularia marina, Colurus 

 uncinatus, Q. caudatus, and Aymrcea striata are encountered in both fresh and 

 salt water : several are found in brackish water. 



Immersion in water is, however, not necessary to their existence : thus they 

 are to be found in the damp earthy deposit from rain-water spouts, and in the 

 detritus of the walls and roofs of houses ; in the moist humus or decaying 

 vegetable matter about trees, and especially upon the moist roots and leaves 

 of mosses and lichens — for example, among the tufts of Brijum and of Hyp- 

 num, from which they may be separated by washing with a little water. 



We have mentioned the peculiar habitat of Albertia, within the intestine of 

 the earth-worm, of which animal it may be accounted an entozoon ; the 

 Notommata Parasitus also leads a parasitic existence within the hollow spheres 

 of VolvoM GJohator; and M. Morren, many years since, gave the following 

 interesting history of the habitat of Botifer vulgaris in the cells of Vauclieria 

 clavata {A. N. H. vi. p. 344) : — 



" The labours of Keeper show that the cells of Sphagnum are sometimes 

 furnished with openings, which place their interior cavity in communication 

 with the air or water in which they are immersed. This skilful observer 

 satisfied himself that, when circumstances are favourable, the Rotifer vulgaris, 

 one of the Infusoria whose organization has been explained by the researches 

 of Ehrenberg, exists in the cells of the Sphagnum obtusifoUum. This grew 

 in the air, in the middle of a turf-pit : but RcBper observed its leaves in water ; 

 he does not mention whether the infusorial animal came from thence, or 

 whether it was previously contained in the cavities of the cells. The general 

 purport of the paper seems to imply that these Rotifers exist in the cells of 

 that part of the plant which was exposed to the air ; and in this case, the 

 presence of an animal so complicated, living as a parasite in the cells of a 

 utricular aerial tissue, is a phsenomenon of the most curious kind in the phy- 

 siology of plants, and the more so as this animal is an aquatic one. 



" I recollected that, the last year of my residence in Flanders, I found at 



