PARAMCECIUM. 95 



tion, so as to propel the creature rapidly through the water. The 



internal part of the cell is very soft, almost fluid, 



and coarsely granular in appearance, containing FIG. 41 - 



many bodies which have obviously been introducd 



from without. This soft internal protoplasm (endo- 



sarc) moves slowly round in a definite direction, 



completing its circuit in one or two minutes, and 



thus carries on a circulation which mixes the 



various matters contained in it. At one point of 



the ectosarc, or cortical layer, an orifice or mouth 



leading to an oesophageal depression is found. This 



orifice is lined by moving cilia, which, by their 



vibrations, drive the food into the oesophagus, 



whence it is periodically jerked into the soft in- Diagram of Par- 



ternal protoplasm or endosarc, together with some amo-cium, showing 



/ i ' i i i digestive cavity. 



water, and thus forms a food vacuole, which is ^ a ^ Body space 

 carried round in the circulation of the ectosarc. filled with soft 

 Besides a well-marked nucleus and nucleolus in ^j^"!^ "'^ 

 the central part of the cell, these paramoecia have taken, (ft) Mouth. 

 one or more clear spaces placed near the surface j) Anus - < d) ^ 



* t r;i't 1 lr VCSlt'IC. 



at the extremities of the animal. These vacuoles (After uchmann.) 

 suddenly contract, and disappear every now and 

 then. When this contraction occurs, fine canals radiating from 

 the contractile vacuole are distended with the clear fluid which 

 has probably entered the vacuole from without. Thus a perma- 

 nent set of water vessels carry fluid from the contractile vacuole 

 throughout the endosarc. 



In such an animal there is a distinct advance of function com- 

 pared with the amoeba ; a more elaborate and specialized method 

 of feeding ; a more systematic and regular circulation of nutri- 

 ent matters ; a respiratory distribution of water by the contrac- 

 tile vesicle and its water canals ; more rapid motion ; and more 

 obvious sensation. 



In the bell animalcule, or vorticella, the same kind of divi- 

 sion of labor exists, but in one of its commonest conditions it is 

 attached by a thin stalk to the stalk of some weed or other object. 

 Besides the ciliary movement, we here find that the general mass 



