OF THE EOTATOEIA. 655 



his gullet, the gradual expansion of his stomach proves that he is not labour- 

 ing in vain. The Monads find to their cost that he is a real Triton amongst 

 the minnows. 



Another mode of capturing similar forms is by emploj'ing a small net, of 

 very fine muslin firmly fastened to a ferruled hoop of brass or iron, a few 

 inches in cii^cumference, and capable of being fitted to a walking-stick or 

 fishing-rod. It has been recommended that the exterior of this hoop should 

 be grooved, so that nets of various degrees of fineness can readily be employed 

 — these being attached merely by means of an elastic ring of vulcanized 

 indian-rubber, di^awn over them and fitting into the metallic groove. By 

 means of a net of this character, the central and deeper parts of a pond can 

 be searched, as, if the gauze be sufficiently fine, the net will retain the larger 

 Rotifera, whilst the water passes fi^eely through it. After making a succes- 

 sion of sweeps through the pond, the net may be everted into a receiver con- 

 taining clear water, and with a little manipulation the animalcules adhering 

 to it may be washed into the vessel. By means of the same net the fluid 

 may be concentrated until at length the rich products of an hour's fishing 

 may be carried home in an ounce phial. But the muslin must be very fine, 

 or the richest of the game will escape. When the large and exquisitely 

 beautiful Floscularian Rotatoria are the objects of search, a different method 

 must be followed. It is but occasionally that they can be met with ; conse- 

 quently the student must be prepared to give time and labour before he 

 succeeds in discovering these lovely objects ; but they are well worth the 

 price. As before obser^^ed, Melicerta, Stejphanoceros, and similar forms are 

 foimd attached to the slender stems and subdivided leaves of CeratopTiyl- 

 lum, Myriopliyllum, Ranunculus aquatilis, the Charce, and similar plants. 

 The method of search which we have found the most successful has been to 

 carry with us to the field a narrow phial of clear white glass or a chemist's 

 test-tube, into which portions of such plants as a pond may contain may be 

 introduced along with a little clean water. The unaided eye, when experi- 

 enced, soon ascertains the presence or absence of the objects sought for ; but 

 the search may be further facilitated by means of a pocket-lens of low 

 magnifying power. If, after selecting several fragments di^awn from different 

 parts of a pond, these do not reveal traces of some of the Ploscularians, it is 

 probable they do not exist there, and we may proceed to some new fishing- 

 groimd ; but if an isolated individual be detected, every clump of aquatic 

 vegetation in the pond should be carefully searched ; for, as is the case mth 

 Volvox and many other microscopic organisms, there will be found in some 

 part of the water a colony where Malthusianism has no place, and to which 

 the isolated individual first found bears the same relation as the trappers and 

 backwoodsmen of the west do to the swarming communities of Boston and 

 New York. 



One remarkable circumstance must be borne in mind by the animalcule- 

 hunter. If he happens to remember a pond where some rare species 

 abounded last year, let him not again turn thither in search of it, as the 

 chances will not be in his favour. These creatures rarely exist in the same 

 water duiing two successive years. The reasons for this are not easily ascer- 

 tainable. The remark is equally applicable to Volvox and the Desmidieac. 

 The search will be most productive if prosecuted on new ground. It may be 

 remarked that the Floscularian Rotatoria are usually discovered accidentally, 

 rather than by predetermined search. Respecting the marine Rotatoria but 

 little is known. The class appears to have but few representatives in salt 

 water, contrasted with their abundance elsewhere. Nevertheless some may 

 occasionally be observed whilst examining corallines and seaweeds under 



