VIII. 



THE PROTEUS ANIMALCULE {Amoeba) AND THE 

 COLOURLESS BLOOD CORPUSCLE. 



Amcebce are minute organisms of very variable size which 

 occur in stagnant water, in mud, in damp earth and else- 

 where, and are frequently to be obtained by infusing any 

 animal matter in water and allowing it to evaporate while 

 exposed to direct sunlight. An Amoeba 1 has also been 

 found living, apparently as a parasite, in the diseased skin 

 of the sheep. 



The Amoeba has the appearance of a particle of jelly, 

 which is more or less granular and fluid in its central 

 parts, but usually becomes clear and transparent, and of 

 a firmer consistency, towards its periphery. Sometimes 

 Amoeba are found having a spherical form and encased 

 in a structureless sac, and in this encysted state they ex- 

 hibit no movements. More commonly, they present in- 

 cessant and frequently rapid changes of form, whence the 

 name of "Proteus Animalcule" given to them by the older 

 observers; and these changes of form are usually accom- 

 panied by a shifting of position, the Amoeba creeping about 

 with considerable activity and, in most cases, with no con- 

 stancy of direction. 



The changes of form, and the movements, are effected 



1 A. parasitica. New S. Wales. 

 M. 24 



