2 04 COLOURLESS BLOOD CORPUSCLES. 



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 improper pabulum, cold, a high tem- 

 perature, &c. the movements become very slow, and then 

 cease altogether. Under circumstances adverse to active 

 movement and increase, but not sufficiently unfavourable to 

 destroy it at once, the organism usually becomes spherical, 

 and the trace of soft formed material upon its surface in- 

 creases until a firm protective covering, envelope, or cell- 

 wall results. In this way the life of the bioplasm is pre- 

 served until the return of favourable conditions, when the 

 living matter emerges from its prison, grows, and soon gives 

 rise to a colony of new amoebae, which exhibit the move- 

 ments characteristic of their progenitors. 



Colourless Blood Corpuscles. The blood, like the tissues 

 of the body, consists of bioplasm and formed material. The 

 latter is partly in a soft semi-solid form (red blood cor- 

 puscles) and partly fluid (serum) being a solution of 

 different substances. 



The bioplasm of the blood exists in the form of i, 

 White blood corpuscles, recently called Leucocytes ;* and 2, 



* The term leucocyte (XtvKOQ white, KVTOQ cell) is very unfortunate, 

 seeing that the bodies thus named are neither white nor cellular. 

 They have no cell-wall, but are perfectly naked masses of bioplasm. 

 Two kinds of leucocytes have been described, the moving and the fixed 

 leucocytes, but unfortunately all leucocytes move. The so-called fixed 

 leucocytes have moved, and are capable of moving. Leucocytes differ 

 only as regards the extent and rapidity of their movements. It is not 

 even possible to conceive a leucocyte or any particle of living matter 

 which does not move. I venture to think such terms as blood-bioplast, 

 lymph-bioplast, pus-bioplast, tissue-bioplast, nerve- and muscle-bioplast, 

 &c., have many advantages over the terms leucocyte, sarcocyte, &c., for 



