ITS PHYSICAL, CHEMICAL, AND STRUCTURAL CHARACTERS. 163 



whilst those which present an unusual resisting power, he infers to be young 

 cells which have not yet acquired the normal characters of the red corpuscles. 1 



144. The Red Corpuscles, when freely floating in the Liquor Sanguinis of 

 blood no longer in motion, exhibit a marked tendency to approximate one an- 

 other; usually coming into contact by their flattened surfaces, so that a number 

 of them thus aggregated present the appearance of a pile of coins; or, if the 

 stratum be too thin to permit them to lie in this manner, partially overlapping 

 one another or even adhering by their edges, which then frequently become 

 polygonal instead of circular. The corpuscles, when thus adherent, resist the 

 influence of forces which tend to detach them, and will even undergo consider- 

 able changes of shape, rather than separate from each other : if forced asunder, 

 however, they resume their normal form. After thus remaining adherent for a 

 time, they seem to lose their attractive force ; for they are then seen to separate 

 from each other spontaneously. This peculiar tendency to aggregation is doubt- 

 less one of the circumstances which influences the coagulation of the blood; it 

 is most strongly manifested in inflammatory blood, and assists in the production 

 of the buffy coat ( 189); whilst, on the other hand, it seems to be neutralized 

 by the action of most saline substances, since, if these be added to the blood, 

 the corpuscles do not run together. 



145. Besides the red corpuscles of the Blood, there are others which possess 

 no colour and might seem to have a function altogether different; these are 

 known as the White or Colourless corpuscles (Fig. 12, c). Their existence has 

 long been recognized in the blood of the lower Vertebrata, where, from being 

 much smaller than the red corpuscle, as well as from differing widely in shape, 

 they could readily be distinguished. But it is only of late (chiefly through the 

 researches of Gulliver, 2 Addison, 3 and others), that they have been recognized 

 in the blood of Man and other Mammalia; their size being nearly the same 

 with that of the red corpuscles; and the general appearance of the two (owing 

 to the circular form of the latter, and the absence of a proper nucleus), being 

 less diverse. It is remarkable that, notwithstanding the great variations in the 

 size of the red corpuscles in the different classes of Vertebrata, the dimensions 

 of the colorless corpuscles are extremely constant throughout; their diameter 

 seldom being much greater or less than l-3000th of an inch in the warm-blooded 

 Vertebrata, and 1 -2500th of an inch in Reptiles. This holds good even in those 

 animals the Musk-Deer, and the Proteus which present the widest departure 

 from the general standard in the size of their red corpuscles; so that the color- 

 less corpuscle is as much as four times the diameter of the red, in one instance ; 

 whilst it is not one-eighth of the long diameter of the red, in the other. The 

 aspect of the Colorless corpuscles under the microscope is by no means constant ; 

 but their variations seem to depend upon their degree of development, and all 

 gradations from one condition to another may be readily traced. In their early 

 state (in which they most resemble the corpuscles of the chyle and lymph), the 

 cell-membrane can scarcely be distinguished from the large nucleus to which it 

 is applied, unless the cell be distended with water or acetic acid, which enables 

 us to see that the nucleus is a soft, granular, tuberculated mass, which is dis- 

 posed to break up readily into two or more fragments. In a later stage, how- 

 ever (of those, at least, which do not go on to be developed into red corpuscles) 

 we find the nucleus apparently dispersed into numerous isolated particles, which 

 give to the entire cell a somewhat granular and tuberculated aspect; and these 

 particles may sometimes be seen in molecular movement within the cell. When 

 the Colorless corpuscles are treated with a dilute solution of potash, they speedily 



1 Op. cit., band ii. p. 175. 



2 Notes and Appendix to Translation of "Gerber's General Anatomy." 



3 "Transactions of Provincial Medical Association," 1842 and 1843. 



