320 STRUCTURE OF WHEEL-ANIMALCULE. 



said to be born alive, being capable of active locomotion, and ot 

 obtaining their own food, as soon as they quit the body of the 

 parent. Besides the longitudinal muscular bands, we observe 

 transverse lines crossing the body at intervals, which might be 

 supposed to possess the same character, and to contribute to the 

 elongation of the body, by contracting upon the contents of 

 the visceral cavity. But Ehrenberg gives strong reasons for the 

 belief, that these are blood-vessels, passing off from a trunk 

 which runs along the back, like the dorsal vessel of Insects 

 ( 618). Nervous ganglia are suspected to exist in this animal 

 in the neighbourhood of the eyes ; but they cannot be seen in 

 this species as distinctly as in some other Botifera. 



858. This Animalcule, from the activity of its habits, and 

 the variety of the movements it performs, is one of the most 

 interesting objects which commonly present themselves to the 

 microscopic observer. Sometimes it fixes itself by its forked 

 tail to some solid basis, and then sets its wheels (as they appear) 

 into rapid revolution ; at the same time bending its flexible body 

 in various directions, so as to create currents in different parts 

 of the surrounding water. In this manner it draws into its 

 gullet the unfortunate Animalcules which have been affected by 

 the whirlpool it has created ; just like (it has been amusingly 

 remarked by Spallanzani) a certain species of Whale, which, after 

 having driven herrings into a bay or strait, by a blow of its tail 

 produces a whirlpool of vast extent and great rapidity, which 

 precipitates them down its open mouth. The food thus taken 

 in passes at once towards the stomach, and is submitted to the 

 action of the jaws at its entrance, by which it is broken down. 

 By keeping a Wheel- Animalcule for a few days in pure water, it 

 will become almost perfectly transparent in every part, and its 

 alimentary canal will be completely emptied. If some water 

 containing the green or red Cercarioe, or any other small coloured 

 animalcules be then added, its voracity will be very amusingly 

 exhibited. They will be very distinctly seen passing into the 

 alimentary canal, as fast as the animal can masticate them ; and 

 this will become distended with their coloured substance. It can- 

 not be questioned that the ciliary movement is here entirely 



