20 AMCEBOID MOVEMENTS OF THE COLOURLESS CORPUSCLES. 



shed blood than in blood still within the circulation. Immediately 

 after blood is shed, an enormous number of white corpuscles disappear 

 (see Formation of Fibrin, p. 47). 



Al. Schmidt estimates the number that remain at r V of the whole originally 

 present in the circulating blood. The proportion is greater in children than in 

 adults (Bouchut and Dubrisay). 



The following table gives the number in shed blood : 



The old method of Welcker for estimating the number of colourless corpuscles is 

 unsatisfactory. The blood was defibrinated, placed in a tall vessel, and allowed to 

 subside, when a layer of colourless corpuscles was obtained immediately under 

 a layer of serum. [It is better to use the hsemocytometer (p. 6) as improved by 

 Gowers.] 



The Amoeboid Movements of the white corpuscles (so-called because 

 they resemble the movements of amoeba) consist in an alternate con- 

 traction and relaxation of the protoplasm surrounding the nucleus. 

 Processes are given off from the surface, and are retracted again (like 

 the pseudopodia of amoeba). 



There is an internal current in the protoplasm, and the nucleus has 

 also been observed to change its form (Lavdowsky). Two series of 

 phenomena result from these movements: (1.) The "wandering" or 

 locomotion of the corpuscles due to the extension and retraction of 

 their processes ; (2.) the absorption of small particles into their interior 

 (fat, pigment, foreign bodies). The particles adhere to the sticky 

 external surface, are carried into the interior by the internal currents 

 (Preyer), and may eventually be excreted, just as particles are 

 taken up by amoeba and the effete particles excreted. [Max Schultze 

 observed that coloured particles were readily taken up by these 

 corpuscles.] 



On a hot stage (35-40C.) the colourless corpuscles of mammals 

 retain their movements for a long time ; at 40C. for two to three hours; 

 at 50C. the proteids are coagulated and cause "heat-rigor" and death. 

 In cold-blooded animals (frogs) colourless corpuscles may be seen to crawl 



