THE MICROSCOPE AS A RECREATION 



129 



colonies of such Monads, as they are called, are to be found on 

 weeds, ceaselessly lashing the water with their flagella, causing 

 a cxirrent which brings particles of food withia their reach. 



Fia. 120.— 

 Monad. 



Fig. 121.— CoUarerl 

 Monad, 



Fig. 122. — Collared 

 Monad in Shells,. 



A further elaboration of this cell wall is found in the Collared 

 Monads, which are possessed of a transparent cup made from an 

 extension of the hardened margin of their body. In the centre of 

 this the flagellum vibrates, bringing a steady flow of water into 

 this''^cup or collar. This is the simplest form, but in a more 

 complicated one these Collared Monads have provided themselves 

 with transparent shells of most elegant forms, to 'the bottom of 

 which they anchor themselves. They retreat right into them 

 f orTprotection from danger, but are found extended when engaged 

 in finding their food. 



Thus a series of creatures are met with which possess a shell 

 of the same simple type, consisting of nothing but a piece of jelly 

 with a nucleus and a bubble, but showing great diversity ofJform 



as regards the struc- 

 ture of the wall of the 



cell in which the jelly 



is contained. 



The development of 



a single Flagellum has 



been traced, but now 



we come to the CiUata, 



which have rows of hairs. 



If we imagine the soft, 



jelly-like exudations of 



the Heliozoa to be 



hardened and given a 

 vibratile motion, we have the simplest form of Ciliate, just a tiny 

 ball with rapidly vibrating hairs all over it, these giving it a con- 

 tinuously rolling movement. Myriads of such creatures in difierent 

 forms exist, some brilliantly coloured, some perfectly transparent. 



Fig. 123.— Ciliata. 



Fig. 124.— 

 Vorticellse. 



