AMCEBA. 



37 



base or bulb, pushing the firm and already formed tissue 

 before it. In the first case, the germinal matter is increasing 

 at the extremity of a filament which it spins behind it as it 

 moves on ; in the last, the tissue already formed is pushed 

 on by the production of new texture in its rear. The ex- 

 tremity of the hair is its oldest part, and nearest to the root 

 is the tissue which was most recently formed. But whe- 

 ther germinal matter moves on in its entirety, or, advancing 

 from a fixed point, forms a filament, a tube, or other 

 structure which accumulates behind it, or itself remains 

 stationary while the products of formation are forced on- 

 wards in one direction, or outwards in all, the nature of the 

 force exerted is the same, and due to the marvellous power 

 which one part of a living mass possesses of moving in advance 

 of another portion of the same, as may be actually seen to occur 

 in the humble amoeba, in the mucus- or in the white blood- 

 corpuscle from marts organism, as well as in the pus corpuscle 

 formed in disease. 



Amoeba. Among the simplest living things known to us 

 are the amoebae, which might be almost described as animate 

 masses of perfectly transparent moving matter. Amoebae, 

 fig. 4, pi. II., can be obtained for examination by placing a 

 small fragment of animal or vegetable matter in a little 

 water in a wine-glass, and leaving it in the light part of a 

 warm room for a few days. I have found it convenient to 

 introduce a few filaments of cotton wool into the water. 

 The amoebae collect amongst the fibres, which prevent them 

 from being crushed by the pressure of the thin glass cover. 



The delicate material of which these simple creatures 

 are composed exhibits no indications of actual structure, 



