CHAP, i.] BLOOD. 39 



of a series of forms shifting its place. Of these ' amoeboid move- 

 ments ' as they are called we shall have to speak later on. 



In carrying on these amoeboid movements the corpuscle may 

 transform itself from a spherical mass into a thin flat irregular 

 plate; and when this occurs there may be seen at times in the midst 

 of the extended finely granular mass or cell body, a smaller body 

 of different aspect and refractive power, the nucleus. The normal 

 presence of a nucleus in the white corpuscle may also be shewn by 

 treating the corpuscle with dilute acetic acid, which swells up and 

 renders more transparent the cell body but makes the nucleus more 

 refractive and more sharply defined, and so more conspicuous, or 

 by the use of staining reagents, the majority of which stain the 

 nucleus more readily and more deeply than the cell body. The 

 nucleus is in some cases a spherical mass about 2 3 fju in dia- 

 meter, but it differs both in size and in form in different corpuscles; 

 of these differences we shall speak presently. 



The cell body of the white corpuscle may be taken as a good 

 example of what we have called undifferentiated protoplasm. 

 It may perhaps be best considered as consisting of a uniformly 

 transparent but somewhat refractive material forming the ground 

 substance or basis, in which occur vacuoles of varying size but 

 all for the most part minute, and in which are imbedded particles 

 also of varying size but also for the most part minute. Some 

 maintain that the ground substance exists in the form of a net- 

 work, the interstices of which are filled up either with fluid or 

 with some material different in nature from that of which the 

 bars of the network are composed ; but without entering into the 

 discussion of a debated question, we may say that the evidence 

 for the natural existence of such a network is not convincing. 

 The imbedded particles are in some cases extremely small, and 

 for the most part distributed uniformly over the cell body, giving 

 it the finely granular or even hyaline aspect spoken of above ; in 

 other cases however the particles are relatively large and ob- 

 viously discrete, making the corpuscle coarsely granular, the coarse 

 granules being sometimes confined to one or another part of the 

 cell body. These particles or granules, whether coarse or fine, vary 

 in nature : they behave differently towards various staining and 

 other reagents. Some of them, as shewn by their greater refrac- 

 tive power, their staining with osmic acid, and their solution by 

 solvents of fat, are fatty in nature ; others may similarly be shewn 

 by their reactions to be proteid in nature ; and in certain cases 

 some of the granules are carbohydrate in nature. 



The material in which these granules are imbedded, and which 

 forms the greater part of the cell body, has no special optical 

 features ; so far as can be ascertained it appears under the micro- 

 scope to be homogeneous, no definite structure can be detected in 

 it. It must be borne in mind that the whole corpuscle consists 

 largely of water, the total solid matter amounting to not much 



