TISSUES OF THE BODY. 



113 



Fig. 115i Coloured blood-cor- 

 puscles from the human 

 being, a toe; rf, a colourless 

 cell or so-called lymph-cor- 

 puscle. 



to deal with cells engaged in the process of formation, with all the differ- 

 ences incident to their various stages of development. We have pos- 

 sibly also to deal with others engaged in retrograde metamorphoses. We 

 meet, therefore, in one and the same body several kinds of these cells. 

 But let us look to their characters. 



The colourless cells of human blood appear when at rest, or in a life- 

 less condition, of spheroidal form, and varying considerably as to size. 

 Small examples measure on an average only about 0'0022, while those of 

 larger dimensions may be of the same size as the red corpuscles. They 

 usually, however, exceed the latter in magnitude, ranging from 0'0077 to 

 0'0120 mm. As the result of measurements made on those of my own 

 blood, I have found their usual diameter to be 0-0091 mm. 



The appearance of these cells is finely granular, but the granules show 

 usually no molecular motion. Under high mag- 

 nifying power, however, this may be seen as in 

 other lymphoid cells. Their contour is also more or 

 less rugged. In most cases the molecules of pro- 

 toplasma are very small and delicate, but in some 

 isolated specimens we find considerably larger, 

 dark particles, consisting of fat, imbedded in the 

 interior. These have been probably taken up 

 from without (fig. 116, 4). The nucleus, enve- 

 loped in the smaller cells by a thin layer only of 

 protoplasm, is in many cases not to be seen with- 

 out the aid of reagents. 



In some it may be rendered visible by the simple addition of water : 

 this, however, causes a change in its appearance, and the cell is at the 

 same time puffed out to a certain extent, and acquires a smoother and 

 more delicate contour. The action of acetic acid, also, brings it rapidly 

 into view. Thus treated, the nucleus is not unfrequently smooth (fig. 

 116, 6), but it is usually more or less rugged (7, 8), containing in its 

 interior a nucleus. In form it is roundish m ^ 



or elongated, and frequently irregular, espe- 

 cially after the prolonged action of acetic 

 acid. The diameter of the nucleus is 

 mostly about 0-0077-0-0052 mm. It may 

 frequently appear reniform (9), and in other 

 cases consists of two or three portions lying 

 in contact with one another (10, 11). In 

 consequence of the prolonged action of the 

 reagent just mentioned, these three portions 

 may become separated from one another by 

 considerable intervals. Finally, we meet 

 with cells whose nuclei have in this manner 

 been split up into four, five, six (12), or 

 even seven fragments. In addition to all 

 this, it must be borne in mind that some isolated lymph-corpuscles are 

 destitute of nuclei, so that the variety met with in the colourless blood- 

 cell is not inconsiderable. 



Compared with coloured cells, the white are somewhat less sensitive 

 towards reagents. Observation of floating blood-cells teaches likewise that 

 the colourless corpuscles roll about with less ease, adhere more frequently, 

 and in general change their position with more sluggishness than the 



i*> 



.()' ef 



Fig. 116. Human colourless blood- 

 corpuscles. From 1 to 3, ordinary 

 unchanged cells; 4, one rich in fat 

 granules; 5, commencement of the 

 action of water; appearance of the 

 nucleus from 8 to 11 ; 12, the nucleus 

 divided by the action of acetic acid 

 into six pieces ; 13, free nuclei 



