CHAPTER I 



THE PROTOZOA 



THESE are the simplest forms of animal life, each individual 

 consisting of one cell only, a simple speck of that com- 

 pound which Professor Huxley termed " the Physical basis 

 of life " Protoplasm. 



A great number of forms live in fresh water e.g. the so- 

 called animalculce of stagnant pools but many are marine. 

 Among these is one of comparatively large size easily 

 visible to the unaided eye. It is a globe-shaped organism, 

 transparent as the water in which it lives, with a threadlike 

 process serving as organ of locomotion, termed a flagellum. 

 This is Noctiluca miliaris. In some parts of our seas it 

 swarms. As its generic name ( = Night-light) implies, it 

 is luminous, and contributes in a large measure to the 

 phenomenon of phosphorescence of the sea. 



One division of the marine protozoa, termed the 

 Rhizopoda, secrete shells either of silica or of carbonate of 

 lime, always of very beautiful patterns. This division 

 embraces two orders, Radiolaria and Foraminifera. The 

 former, also known as Polydstina, has shells of silica, 

 the Foraminifera, as a rule, shells of carbonate of lime. 

 As the latter are the more conspicuous, and the most easily 

 obtained and studied, we shall restrict ourselves to these, 

 repairing to a sandy shore for our observations. 



The stretch of sand before us, the tide having receded, 

 and the sun partially dried its surface, is seen to present 

 different shades of colour, the whitey-brown tint of quartz 

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