166 THE SO-CALLED STOMACHS 



some such transparent substance. When this is complete, the 

 prepared morsel glides through an invisible outlet into the seem- 

 ingly simple cavity of the body. If, now, the course of these 

 pellets is carefully watched and noted, we must conclude that 

 they are subjected to the action of something which has a defi- 

 nite position and a corresponding effect upon them, for they do 

 not float about hither and thither indiscriminately, but follow 

 each other in regular succession ; passing from the throat back- 

 wards along the left side to the end of the body, they there turn 

 forwards in a stream close to the back, and at the same time 

 gradually move over to the right side, until they reach the head, 

 (H,) and then, making a second turn, they follow the ventral 

 line of the body past the mouth to a point which is a short dis- 

 tance behind the place where they left the throat, but consider- 

 ably to one side of it, in fact, just about half-way between the 

 right and left of the body. Daring this circuit, they gradually 

 lose their jelly-like envelope, and the minute particles of indigo 

 are, one by one, separated from the pellet and subjected to the 

 process of digestion until whatever nourishment was in them is 

 extracted, and then they cease their circulation and gather at the 

 point which I have just mentioned. There they wait until a 

 considerable mass of rejectamenta is formed, when the promi- 

 nence, (a,) which has been formed a short time before, opens at 

 the end and allows it to pass out, and then subsides and leaves 

 not the least trace of an outlet. 



Why, therefore, I would ask, ought we not to attribute to 

 Paramecium a definite digestive or intestinal canal, seeing that 

 the food passes in such a strictly confined channel ? How well 

 marked the boundary of this canal is, can only be inferred from 

 the spiral course which the food pursues in passing from the 

 mouth to its orifice of expulsion. This might be compared, by 

 some, to the circulation of fluids in the cells of plants ; but, from 

 numerous and extended observations of my own, not only upon 

 the familiar and well - known examples, such as Vallisneria, 

 Naias, Udora, Chara, Nitella, Zygnema, the hairs of the Nettle, 

 Tradescantia, and Circea, but also upon the cells of the pulp of 



