THE BLOOD. 115 



and more recently by M. Malassez. It consists in diluting 

 with a certain quantity in distilled water, collecting a portion 

 of this mixture in a capillary tube, and deciding, by the aid 

 of a graduated micrometer, or simply by that of the micro- 

 scope, what is the quantity contained in a portion of the tube. 



The red globules, or, properly, blood globules, are small 

 disks, excavated on both surfaces, and thicker at the edges 

 (Fig. 32) ; their diameter is T J^ of a millimetre, and their 

 thickness is F J^. 



Considered histologically, the red globules are small mnsses 

 of protoplasm, combined 'with certain chemical compositions 

 (see, farther on, globuline, hematine, etc.) ; tt f 

 seen in section, these elements appear in QJS e 

 the form of a biscuit, narrow in the mid- Q8SI /, o<& 

 die, and widening at the two extremities * A&fff 



(Fig. 32, c). In front, they appear as disks 9 



of a yellowish color, darker at the edges, y^ ^ 



more transparent towards the centre (Fig. Blood globules of an 

 r. \ mi j- i ' adult man.* 



32, a). I here are no distinct nuclei or 



envelope, but a very thin limiting layer, which seems to in- 

 dicate the presence of an enveloping membrane, or, at least, 

 of a sort of girdle, more condensed than the globules, and 

 having a different composition. The absence of membrane 

 has been thought to be demonstrated by the deformities 

 which these globules undergo when subjected to a tempera- 

 ture of from 40 to 45 (Ranvier), or to the action of car- 

 bonate of potash (Dujardin). Under these circumstances 

 they become flatter, and change their shape into that of a 

 number of caps or cups, whose edges have been recently and 

 regularly united to each other. We observe the same phe- 

 nomena, however, under like circumstances, in the bodies of 

 the infusoria (Rouget), which certainly have a covering, or, 

 at least, a cortical layer (hautschicht of the Germans). Fi- 

 nally, by the action of picric or chromic acid, we discover a 

 distinct membrane ; this is still more visible in the batrachi- 

 ans, in which, under the influence of hibernation, colorless vacu- 

 oles, or fragments of the coloring matter, radiating like the 

 spokes of a wheel, are formed in the blood globules (Rouget). 



* a, Ordinary red globule, having the form of a disk, i, White globule. 

 c, Red globules, seen from the side, being placed upon their edge, d, Red glob- 

 ules, piled one upon the other, like coins, e, Red globules, with shrunken edges, 

 a part of the contents of which has been lost by exosmosis, whence their shrunken 

 or crenated appearance. /, Red globules (the' edges being uneven, and the sur- 

 face exhibiting a swelling resembling a nucleus); g, still more shrivelled; 

 h, final degree of crenation. 280 diarn. (Virchow.) 



