24 



PHYSIOLOGY OF THE INVERTEBRATA. 



different functions do not follow the same lines in the animal 

 series. Nor will the advance of particular functions keep 

 pace with the advance in anatomical structure. As far as 



yi^j' ■." 



Fig. 2.— Various Pkotozoa. 



A = Gregavina. B = Amceba. C = Magosphaera. D = Actinophrys. 



E = Actinosphserium. F = Part of E highly magnified. 



V = contractile vacuole, n = nucleus. 



structure is concerned, the Gh'egarina ranks higher than the 

 Amceba. 



(b) The Amceba. — In the Protoplasta, to which the Amosld/ 

 belongs, we have a distinct advance in the mechanism of 



