THE WHITE CORPUSCLES. 29 



stated, are readily distinguishable from the red cor- 

 puscles by their want of color and their pale, granu- 

 lar aspect, we usually notice, if the room is moder- 

 ately cool, and provided they are not pressed down 

 by the cover-glass, that they are spheroidal and com- 

 pletely motionless, exhibiting no indications of vital- 

 ity. Some of them may be noticed to contain a small 

 group of well-marked granules, much coarser than 

 the excessively fine granules .which pervade the 

 whole substance; and in conformity with this it is 

 usual to describe two kinds of white corpuscles the 

 finely granular, and the coarsely granular but there 

 would not seem to be any very essential difference 

 between the two. As a rule, before the addition of 

 reagents, no nucleus is visible in either variety, 

 although, as will be afterwards seen, one or more is 

 always present in each ; the nuclei are delicate, how- 

 ever, and readily obscured by the granules of the 

 protoplasm. If the room is tolerably warm it may 

 happen that the white corpuscles no longer preserve 

 their rounded outline, but that from one side or an- 

 other of a corpuscle a bud -like process extends itself, 

 to be again retracted into the body of the corpuscle; 

 spontaneous changes of form being thus effected 

 which resemble those which are presented by the 

 common fresh-water amoeba, and are hence termed 

 a amoeboid;" but in a cold preparation of human 

 blood, like that under examination, these movements 

 are seldom extensive, and do not serve to effect an 

 actual change of place in the corpuscles such as we 

 shall see to be the case in a preparation which is 

 artificially warmed. 



Further, there may generally be seen in a prepa- 

 ration of blood a number of excessively minute pale 

 granules, which, if present in quantity, may be 

 closely grouped together here and there into masses 

 or "colonies" of various shapes and sizes (see Fig. 8, 

 ), which the beginner is sometimes apt to mistake 

 for white blood-corpuscles. But the objects in ques- 

 tion have a much fa in tor aspect ; and although under 



