INFUSORIA. 27 



this fissure is effected in a longitudinal direction, 

 the separation gradually proceeding from the posterior 

 to the anterior portion of the body. Examples of 

 both these modes of increase are delineated in the 

 appended engravings (Figs. 12 and ] 3). 



FlG. 14. FIGURE OF COLEPS AND CHILOMONAS. 



If the organization of these animalcules were as 

 simple as it was supposed to be a few years ago, 

 when they were thought to be mere specks of living 

 jelly imbibing nourishment through all parts of the 

 soft texture of their bodies, this kind of spontaneous 

 division would be a very simple matter, and every 

 step of the process easily understood : a little observa- 

 tion, however, will show that there are circumstances 

 attending this operation of a very inexplicable cha- 

 racter. Some species, as for example, Prorodon 

 teres* represented in our engraving (Fig. 12, b\ are 

 furnished with a very curious mouth surrounded by 

 a cylinder composed of horny teeth, through the 

 agency of which their food is seized and swallowed. 

 Should a deed of separation, therefore, have to be 

 drawn up preparatory to the act of division, it might, 

 be a puzzling question for the Infusorial lawyers to 

 settle which half should have the mouth. Even this 

 difficulty has, however, been provided for; and, ac- 

 cordingly, a new mouth and a new dental cylinder is 

 seen to sprout from the hinder half, before the 



* irpapa, prora, fore part ; oSbvs, b6v TOS, odous, odontos, a tooth. 



c 2 



