T 



CHAPTER VIII. 



Details of Protozoa. 

 HE Protozoa are divided into three orders. 



I. — Gregarinidce. 

 II. — Rhizopoda. 

 III. — Infusoria. 



I. The Gregarinidce consist of minute protozoa, parasitic in the 

 interior of insects, &c, and like other internal parasites are colour- 

 less, as we should expect. 



II. The Rhizopoda may, for our purpose, be divided into the 

 naked forms like Amoeba, and those which possess a skeleton, such as 

 the Radiolaria, the Foraminifera and the Spongia. 



Of these the naked forms are colourless, or uniformly tinted, 

 excepting the flush already described as emphasizing the contractile 

 vesicle. 



The Foraminifera are the earliest animals that possess a skeleton 

 or shell, and though generally very small, this shell is often complex, 

 and of extreme beauty, though their bodies retain the general sim- 

 plicity of the protozoa, indeed, they are said to possess no contractile 

 vesicle. Still the complexity of their shells places them on a 

 higher level than the naked rhizopoda. 



In these animals we find the first definite colour, not as a pattern, 

 but as simple tinting of the protoplasm. The general hue is 

 yellowish-brown (as in Amoeba), but deep red is not uncommon. The 

 deepest colour is found in the oldest central chambers, becoming 

 fainter towards the periphery, where it is often almost unrecog- 

 nisable.* 



* Leidy. Rhizopoda of N. America, p. 16. 



