Prof. Ehrenberg's Researches on the Iiifusoria. 215 



extremity. In the genus ParamcBcium, however, it is in the 

 middle of the length of the animal. The Kolpoda cucullus 

 possesses a sort of lip surrounding its margin. 



The ciliae play a very important part in the economy of this 

 class of animals. They may be considered as the principal or- 

 gans of taste, of touch, and of propulsion. When the animal 

 is at rest, they are often quite imperceptible, but on the addition 

 of a small proportion of colouring hquid. to the drop of water, 

 they become very apparent, being in a state of great activity, 

 seeming to be the principal agents by which they excite those 

 currents which afford so beautiful a spectacle under the field of 

 the microscope*. In the Monas pulvisculus, and other larger 

 monads, their number amount to 10 or 20, and we may from this 

 conclude that they exist even in the smallest monad. They some- 

 times surround the mouth in a single row ( Vort'icclla convalla- 

 ria. Rotifer vulgaris), sometimes in a double row {Vorticella 

 citrina) ; occasionally they extend in regular lines, or are irre- 

 gularly dispersed over the whole surface of the body. The for- 

 mer disposition occurs in the Leucophrys piriformis and patula, 

 the latter in the Actinophrys sol. They occupy, in other cases, 

 only one side of the body {Kolpoda cucullus). 



An cesophagus can only properly be said to belong to those 

 which, like the Eospliora najas and Hydatina senta, possess a 

 notable contraction between the mouth and the stomach. This 

 is especially distinct in the latter, where I have distinctly traced 

 the passage of individual coloured globules along this narrow 

 canal from the mouth into the intestine. 



Perhaps this is the most appropriate place to notice an organ 

 of a very obscure nature, which Dr Ehrenberg dignifies with 

 the name of a pancreas. It is in the form of two kidney-shaped, 

 greyish-white, glandular-looking, transparent bodies, which are 

 placed on each side of the upper extremity of the intestine, 

 firmly connected to, and closely embracing it. Dr Ehi-enberg 

 regards them as bearing a greater analogy to the pancreas than 



• One of the most favourable moments for seeing these ciliae to advantage, 

 particularly in those species in which they invest the whole surface of the 

 body, is when the drop of fluid under the microscope is nearly dry. when they 

 may be seen elongated to their utmost, in a state of great activity; or if the 

 animal be nearly expiring, in a state of rigid erection. 



