VITAL MOVEMENTS. 41 



appearance under a magnifying power of 5,000 diameters of 

 some of the most minute amoebae I have been able to 

 discover. (Plate II, fig. 3.) Several of these were less 

 than 100 1 ooTJ th of an inch in diameter, and yet were in a state 

 of most active movement. The alteration in form was 

 very rapid, and the different tints in the different parts of 

 the moving mass, resulting from alterations in thickness, 

 were most distinctly observed. The living bodies might, in 

 fact, be described as consisting of minute portions of very 

 transparent material, exhibiting the most active movements 

 in various directions, in every part, and capable of absorbing 

 nutrient materials from the surrounding medium. A portion 

 which was at one moment at the lowest point of the mass 

 would pass in an instant to the highest part. In these 

 movements one part seemed, as it were, to pass through 

 other parts, while the whole mass moved now in one, now 

 in another direction, and movements in different parts of 

 the mass occurred in directions different from that in which 

 the whole was moving. What movements in lifeless matter 

 can be compared with these ? 



The movements above described continue as long as the 

 external conditions remain favourable ; but, if these alter 

 and the amoeba be exposed to the influence of unfavourable 

 circumstances as altered pabulum, cold, &c. the move- 

 ments become very slow, and then cease altogether. The 

 organism becomes spherical, and the trace of soft formed 

 material upon the surface increases until a firm protective 

 covering, envelope, or cell-wall results. In this way the 

 life of the germinal matter is preserved until the return of 

 favourable conditions, when the living matter emerges from 



