22 



PHYSIOLOGY OF THE INVERTEBRATA. 



nuclein. Dr. Schmitz has named this small globule pyrenoid.''^ 

 The function of the pyrenoid is the formation of starch and 

 similar carbohydrates. This is a process of digestion akin 

 to the vegetal kingdom. 



It is interesting to note that " the Euglcnw (belonging to 

 the Flagellata) might nourish themselves as animals do, for 

 they have a mouth and a digestive apparatus. The buccal, 

 or oral, aperture opens in the anterior end at the base of the 



Fig. I. — EuGLENA. 



A = C, contractile vacuole ; E, eye or ocular spot ; P, disk of 

 paramylone ; N, nucleus; Ch, chromatophores. 



B = M, mouth; E, eye; D, contractile reservoir ; C, contractile 

 vacuole. 



flagellum, and is connected with a short gullet or oesophagus 

 (Fig. i). Nevertheless the EiKjlena is never seen using its 

 mouth for swallowing alimentary particles. A curious problem 

 is involved here. If it is true, as has been claimed, that it is 

 the function that makes the organ, how do we explain the 

 existence, and especially the genesis, of this digestive 

 apparatus, which performs no function?" 



The second type of nutrition or digestion in the animal 



* From TTvprjv, a nucleus. 



