of the Bed Blood Corpuscle. 25 



substance coalesces, on the removal of its haemato-crystallin, into 

 a jelly-like drop, is negatived by the fact that occasionally, as is 

 also described by Professor J. C. Dalton, one side of a corpuscle, ren- 

 dered colourless by water, fails to assume a convex form, being 

 apparently sucked in by the other side, which becomes exaggeratedly 

 convex, until the whole corpuscle resembles a bell, or more accu- 

 rately a liberty cap, in shape, without any tendency to present the 

 outline of a sphere. Second, the appearance of the specimens I 

 have examined strongly indicates the existence of a dense mem- 

 brane, thrown into folds around the extremities of projecting crys- 

 tals, just as a loosened tent cloth would be around the point of a 

 cane thrust against it from the inside ; and further, the movement 

 of the crystals, when partly dissolved, around the nucleus but con- 

 fined within the corpuscle as described in the early part of this 

 paper, both tend to show that the cavity of the corpuscle between 

 the nucleus and the membranous envelope is quite unoccupied by 

 solid matter. Third, the perfect freedom with which one side of 

 the cell wall of a red blood globule from the Menobranchus when 

 acted upon by water may float in until it touches the nucleus, and 

 out again to its own place, will, I think, furnish conclusive evidence 

 to anyone who sees it as I have done, against the existence of a 

 porous substance which maintains the shape of the blood disk. 



From these • researches I therefore conclude that the older 

 theory, which asserts that the red blood corpuscles of the vertebrata 

 generally are vesicles, each composed of a delicate, colourless, in- 

 elastic, jjorous, and perfectly flexible cell wall, enclosing a coloured 

 fluid, sometimes crystallizable, cell contents, which are freely soluble 

 in water in all proportions, explains the physical phenomena pre- 

 sented by red blood globules far more satisfactorily than any other 

 hypothesis which has hitherto been advanced ; and, moreover, that 

 the usual bi-concave discoid form of the corpuscles in most mammals, 

 as well as the changes of shape which they undergo in fluids of 

 greater or less specific gravity than the liquor sanguinis, becoming 

 crenated in denser, and globular in rarer liquids, are such as to be 

 perfectly explicable by the light of our present knowledge in regard 

 to the laws of the exosmosis and endosmosis of fluids through mem- 

 branes ; the equihbrium of these forces being maintained in normal 

 serum, and one or the other being rendered preponderant if the 

 specific gravity of that fluid is disturbed. — Transactions of the 

 American Medical Association. 



