THE BIOLOGY OF DAILY LIFE. 47 



toplasm, containing larger or smaller bright 

 granules. These granules, though usually of a 

 fatty nature, are in some kinds of blood, 

 notably horses', of a reddish colour, and these 

 corpuscles are supposed by some observers 

 (Semmer and Alexander Schmidt) to be inter- 

 mediate between red and white corpuscles. 

 The protoplasm of the colourless corpuscles 

 contains glycogen (Ranvier, Schafer). In the 

 blood of the lower vertebrates the corpuscles are 

 much larger than in mammals. But in all cases 

 they consist of protoplasm, include one, two, 

 or more nuclei, and show amoeboid movement. 

 This may be observed in corpuscles without 

 any addition to a fresh microscopic specimen 

 of blood, but it always becomes much more 

 pronounced on applying artificial heat of about 

 the degree of mammals' blood. It is then seen 

 that they throw out longer or shorter fila- 

 mentous processes, which may gradually 

 lengthen or be withdrawn, appearing again 

 at another point of the surface. 



" The corpuscle changes its position, either 

 by a flowing movement of its protoplasm as a 

 whole, thus rapidly creeping along the field of 

 the microscope, or it may push out a filamen- 

 tous process and shift the rest of its body into 

 it. During this movement the corpuscle may 

 take up granules from the surrounding fluid. 



u 14. The white corpuscles of the same 

 sample of blood differ in size and aspect within 

 considerable limits, some being half the size 

 of others, some much paler than others. The 



