14 ELEMENTS OF HISTOLOGY. [chap. n. 



circulating blood or in blood that has just been 

 removed from the vessels. Their substance is trans- 

 parent granular-looking protoplasm, 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 colourless 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 

 filamentous 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 or be withdrawn, appearing again at another point 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 filamentous process 

 and shift the rest of its body into it. During this 

 movement the corpuscle may take up granules from 

 the surrounding fluid. 



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 smaller examples generally 

 possess one nucleus occupying the greater part of the 

 corpuscle, the larger ones usually include two, three, 

 or even more nuclei, and show more decided 

 amoeboid movement than the others. Division by 



