STRUCTURE OF THE RED BLOOD CORPUSCLES. 407 



It must, I think, in reference to this point, be admitted that 

 important evidence, based on the form of the corpuscles, can be 

 adduced against the view that they consist of vesicles in the 

 sense held by a large number of histologists after the time 

 of Schwann. 



A vesicle filled with fluid, the parietes of which are yielding, 

 and which again floats freely in another liquid, might be con- 

 ceived to assume almost any form rather than of a body with 

 two concave surfaces, as in Mammals, or with two convex sur- 

 faces, surrounded by a circular or elliptical zone of a certain 

 thickness, as in Birds, Amphibia, and Fishes. 



Schwann* adduced the assumption of a spheroidal form by 

 the blood corpuscles on the addition of water, as a proof of their 

 vesicular nature, maintaining that if they were not so they 

 might indeed swell up and become colourless, but that they 

 would retain their form like a sponge on the imbibition of fluid. 

 The explanation of the action of water producing tension of the 

 membrane, in consequence of the fluid contents of the vesicle 

 increasing by endosmose, was at this time very generally accepted, 

 just as the shrivelling of the surface, on the addition of saline 

 solutions, was regarded as a consequence of a diffusion current 

 setting from the interior. Briicke,f however, showed that 

 neither the phenomena presented by the imbibition of water, 

 nor after the addition of saline solutions, furnished conclusive 

 evidence of the vesicular nature of the corpuscles. 



If we base our opinion on the experiments performed on the 

 red blood corpuscles by means of mechanical agents, we may 

 exhaust all the various methods, without once meeting with a 

 form which can be indisputably regarded as the torn and 

 empty investing membrane, and the occurrence of which is in 

 no other way capable of being explained ; so again, whatever 

 may be the, changes that induction currents and electrical 

 discharges, as well as freezing, induce in the corpuscles, no 

 condition can at any time be seen directly proving the pre- 

 sence of a membrane. 



* Ueber die Uebereinstimmung in Structur und Wachsthum der thieris- 

 che nund Pflanzlichen Organismen. Berlin, 1839, p. 74. 

 f Berichte der Wiener Akademie, Band xliv., p. 389. 



