CPAPTEE X. 



OF THE DIGESTIVE APPARATUS IH THE ANIMAL SERIES. 



r^iGESTiON is the introduetipn in mass pf aliments into a special 

 organic cavity where these aliments are analysed, elaborated, and 

 absorbed, living usually a residuum which is afterwards expulsed. 

 We see that this function does not exist normally in the y;egetal 

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

 carnivorous plants. It is very interesting to follow along. the 

 anim£|,l series, the specialisation more and more perfect of this 

 grand function. 



Fio. 3. 



AmcEba Sphcerococeus at the different degree^ of its evolution. A, amoeba encysted. Proto- 



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



amoeba come fortliiYom the enveloping m^mb^ne ; C, amoeba comiAencing to divide; Da 



and Dii, amoeba totally divided into two.i^dep«;iid$nim<^!;iee. 



In certain yery , inferior organisms, in certain protozoaries, 



digestion is as completely lacking as in the vegetal kingdom. 



•In l^e ^re^rartn^, for ^ example, the alimentary .substances are 



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



indifEerently, 



