592 



water to a preparation of blood) : "This simple experiment conclusively 

 shows that the corpuscle is composed of a membrane or external en- 

 velope with coloured fluid contents ; for the above reaction is precisely 

 the same as would occur by osmosis with a bladder of the shape of 

 the corpuscle. On the other hand it is entirely inexplicable on the 

 supposition that the corpuscle is composed of a uniform disc -shaped 

 stroma, permeated with coloured substance, which is the view advocated 

 by Brücke and Rollett and adopted by nearly all subsequent writers 

 on the subject, for if this were the case water should swell it out 

 uniformly. 



The same fact is illustrated by the effects of mechanical injuries. 

 If the corpuscles are suddenly pressed they become ruptured and the 

 haemoglobin escapes, leaving the colourless part of the corpuscles as 

 a mere outline. If blood is frozen the ice-crystals which form rupture 

 the envelope and on thawing the haemoglobin escapes into the serum. 

 Electric shocks passed through blood, if sufficiently strong, also rup- 

 ture the delicate envelope of the corpuscles. Dilute acids act like 

 water but decompose the hsemoglobin into colourless proteid (globin) 

 and hsematin, which are both dissolved by the acid. In the case of 

 tannic acid, the products of decomposition are usually precipitated upon 

 the envelope in the form of a small dark red coagulum. Alkalies, 

 even when very dilute, cause a complete disappearance of the red 

 corpuscles, the membranes as well as the haemogiobin being dissolved. 

 Ether or chloroform produce a similar etfect when shaken up with 

 blood, but may not completely dissolve the envelope. The blood or 

 serum of some animals produces decolorization of the red corpuscles 

 of others belonging to diflerent genera. This may be due to the 

 fact that the one is more alkaline or of less specific gravity than the 

 other, but the actual cause has not been determined definitely. So- 

 lutions of common salt, if stronger than 0.6 per cent, produce when added 

 to blood crenation of the corpuscles. This is due to exosmosis, the 

 corpuscles losing water and thereby becoming shrunken. Under like 

 circumstances the blood corpuscles of the frog and newt, which do not 

 exhibit crenation, show a wrinkled appearance of the surface of the 

 corpuscle 1), a phenomenon which is scarcely explicable except by as- 

 suming the presence of a membrane" -). 



1) This wrinkling was described by Ray Laxkester in 1871, and 

 he recognised that it affords clear evidence of the existence of an ex- 

 ternal pellicle to the corpuscle. Quart. Journ. of Microsc. Sc, Vol. 11^ 

 p. 371. 



2) Quain's Anatomy, 10. Edition, Vol. 2, 1893, Histology, p. 210. 



