CHAPTER X. 



OF THE DIGESTIVE APPARATUS IN THE ANIMAL SERIES. 



DIGESTION is the introduction in mass of aliments into a special 

 organic cavity where these aliments are analysed, elaborated, and 

 absorbed, leaving usually a residuum which is afterwards expulsed. 

 We see that this function does not exist normally in the vegetal 

 kingdom. At the most, we can make a slight exception for the 

 carnivorous plants. It is very interesting to follow along the 

 animal series, the specialisation more and more perfect of this 

 grand function. 



FIG. 3. 



Amceba Sphrerococcus at the different degrees of its evolution. A, amoeba encysted. Proto- 

 plasmic mass (c) containing nucleus (b) and nucleole (a); enveloping membrane (d); B, 

 arrueba coine forth from the enveloping membrane ; C, amoeba commencing to divide ; Do 

 and Db, amoaba totally divided into two independent amrebse. 



In certain very inferior organisms, in certain protozoaries, 

 digestion is as completely lacking as in the vegetal kingdom. 

 In the gregarine, for example, the alimentary substances are 

 absorbed in the state of solution by all the points of the surface 

 indifferently. 



