THE PROTOZOA. 



e. The oral groove runs obliquely backwards along the 



ventral surface from near the anterior end to the 

 mouth, which is placed a little behind the middle 

 of the length of the animal. Its ciha are directed 

 towards the mouth, and drive water and food 

 particles into it. 



f. The mouth is an oval aperture in the ectosarc at 



the hinder end of the oral groove, through which 

 the food passes into the endosarc. 



g. The anus is an aperture between the mouth and 



the hinder end of the body. It is visible only at 

 the moment of extrusion of faBcal matter. 

 2. The endosarc is the more fluid granular protoplasm 

 forming the central portion of the cell-body. 



a. The food-vacuoles are spherical spaces in the 



endosarc filled with water containing food- 

 particles. 



b. The circulation of the endosarc is rendered obvious 



by the food-vacuoles and the granules, which are 

 carried round in a definite direction. 



0. The nucleus is an elongated ovoid body near the 

 centre of the cell-body. 



d. The paranucleus is a much smaller body applied to 

 one side of the nucleus, and resembling it in 

 appearance. In some cases both nucleus and 

 paranucleus appear to be situated in the ectosarc 

 rather than in the endosarc. 



t. Reproduction. 



1. Fission is the most usual method, and is effected in 



the following manner. A transverse constriction 

 appears on the surface of the animal, and deepens 

 till the body is divided into two, each having a 

 portion of the original nucleus and paranucleus, 

 and each becoming a perfect Paramecium. 



2. Conjugation is not a mode of reproduction, but is 



closely connected with it. Two Paramecia become 



