654 SYSTEMATIC HISTORY OF THE INFUSORIA. 



scopist must not be afraid of soiling his hands, or have a weakness for kid 

 gloves. Some few Rotatoria assume the habits of Entozoa. Albert ia ver- 

 micularis was found by Dujardin in the abdominal ca\'ities of the earthworm 

 and in the intestine of Limacina ; whilst Albertia crystallina was discovered 

 by Schultze in the intestine of Nais littoraUs. 



Capture of Rotatoria. — The modes of captimng the Rotatoria must vary 

 with the species sought, as will be e\-ident from the remarks made in the 

 preceding section. The simj^lest mode of obtaining the majority of the forms 

 is to collect a quantity of Confervas, Lemnse, or the half-decaying masses of 

 the diiferent pond-weeds, fiUing the vessel with water from the pool in which 

 plants were growing. We have usually found the shallow margins of the 

 pond most productive. On reaching home, the vegetable mass must be well 

 stirred up in the water, in order to detach the animalcules from the plants to 

 which they cling ; and, before they have time to re-attach themselves, the 

 water must be poured off into another vessel, through a piece of muslin or 

 very fine net. All the coarse material is thus got rid of, nothing passing 

 through the strainer but water rendered turbid hj fine particles of half- 

 decayed vegetation suspended in it. But along \\ix\i these vegetable atoms 

 the Rotatoria Avill also pass into the receiving vessel, which must be allowed 

 to stand for a while, allowing the sediment to sink to the bottom, where 

 it will be followed by the animalcules which find nutriment in the half- 

 decayed mass. A small portion of this sediment may noAv be taken up by 

 means of a narrow glass tube, one end of which must be introduced to the 

 bottom of the vessel, whilst the opposite one is closed by the finger or thumb. 

 On removing the latter, the sediment iTishes up into the tube ; and if the 

 upper end of the tube be again closed as before, the contained material can be 

 transferred to the live-box or the glass slide. If the tube be held for a few 

 moments in a vertical position, the upper part being still closed with the 

 finger, the vegetable matter and its accompanying animalcules vnW. sink to 

 the lowest part of the water ; consequently the first di'op escaping fi^om the 

 lower end of the tube will usually be richer than those that follow. If the 

 di'op be received upon a glass sHde, it must be covered over vdih. a piece of 

 thin glass, when it is ready for the microscope, and, unless the pond has been 

 uncommonly barren, the instrument will reveal a rich harvest of Algge, Con- 

 fervae, Desmidieae, Diatoms, and Polygastrica ; whilst amongst all these the 

 Rotatoria ^vill be found sailing from point to point, exploring all the recesses 

 between the vegetable fragments, — now quiescent, as if contemplating the 

 contents of the larder, then, as if dissatisfied with the prospect, sailing away 

 to some more promising pasture. But when a tempting nook presents itself, 

 this restless locomotion ceases, and they attach themselves to some fixed point 

 either by means of a disk-like foot or by using its terminal joints as an anchor, 

 — their trochal disks being for the time drawn in, and comfortably lodged in 

 the anterior part of the body. Its position being faiiiy secui^ed, the animalcule 

 evolves its wheels, at first slowly, but soon increasing their speed. A violent 

 commotion amongst the atoms abounding in the water soon indicates the pro- 

 duction of a miniature whirlpool, which brings a contmuous stream of edible 

 matter within the reach of the hungry traveller. But, though hungry, he is 

 a dainty gentleman, and chooses to select his fare. The bulk of what is 

 drawn towards him by the vortex he has 'created, not suiting his taste, is 

 suffered to flow by, in a continuous stream, like that left by the rocket in its 

 flight. But everything is not thus allowed to pass : the teeth-like jaws of 

 the animalcule are constantly playing against each other with desperate 

 energy, whilst sudden jerks and contractions indicate that the animalcule has 

 made a capture ; and though it is not always easy to see his prey pass down 



