RED BLOOD-CORPUSCLES AND THEIR CONTENTS. 



concerning the cellular nature of which doubts might 

 be permitted, if we did not happen to know that, at 

 certain periods of the development of the embryo, they 

 do contain nuclei. An ordinary red blood-corpuscle must 

 therefore be considered as composed of a closed mem- 

 brane, containing a tolerably tough mass, which is the 

 seat of the colour. Now, in man the blood-corpuscles 

 are, as is well known, flat, disc- or plate- _, 



shaped bodies, with a central depression 

 on each surface, and, when regular in 2^! 

 form, constitute, as it were, a ring, in the 

 centre of which the colour is fainter from 

 the diminished thickness. The contents are generally 

 somewhat summarily regarded as consisting of haema- 

 tine, or the colouring matter of the blood. They are, 

 however, unquestionably very complex, and what is 

 called haematine forms merely a part of them ; how great 

 a part it has not been hitherto possible to determine. 

 Whatever other matters are contained within the blood- 

 corpuscle belong entirely to its chemistry. Certain 

 changes produced by the action of external media con- 

 stitute all that can be seen of them. We observe that 

 the blood-corpuscles, according as they imbibe oxygen, 

 or contain carbonic acid, appear light or dark, whilst 

 they alter their form a little. We know, further, that 



a few are slightly granular, but the greater number more homogeneous ; at * a 

 colourless corpuscle, b. Cells with extremely small, but well defined nuclei, and 

 distinctly red contents, c. After the addition of acetic acid the nuclei are seen in 

 some instances shrivelled and jagged, in several, double ; at * a granular corpuscle. 

 280 diameters. 



Fig. 52. Human blood-corpuscles from an adult, a. An ordinary disc-shaped, 

 red blood-corpuscle ; 6, a colourless one ; c, red corpuscles seen in profile, and 

 standing upon their rims. d. Red corpuscles arranged in the form of rouleaux of 

 money, e. Red corpuscles which have become irregular in outline, and shrivelled 

 through loss of water (exosmosis). /. Shrivelled red corpuscles, with tuberculated 

 margins, and a projection, like that produced by a nucleus, upon the flat surface of 

 the disc. g. A still more shrivelled state. A. The highest degree of shrivelling 

 (melanic corpuscles). Magnified 280 diameters. 



