V] OF BLOOD CORPUSCLES 437 



the volume unchanged; a httle ammonium oxalate impedes or 

 inhibits the change of form, a little serum brings the spherical 

 corpuscles back to biconcave discs again. We are no longer deaUng 

 with simple diffusion, but with phenomena of a very subtle kind. 



Secondly, the form of the corpuscle can be imitated artificially 

 by means of other colloid substances. Many years ago Norris made 

 the interesting observation that drops of glue in an emulsion assumed 

 a biconcave form closely resembling that of the mammahan cor- 

 kpuscles*; the glue was impure and doubtless contained lecithin. 

 Waymouth Reid made similar emulsions of cholesterin oleate, in 

 which the same conformation of the drops or particles is beautifully 

 shewn; and Emil Hatschek has made somewhat similar biconcave 

 bodies by dropping gelatine containing potassium ferrocyanide into 

 copper sulphate or a tannin solution. Here Hatschek beheves that 

 his biconcave drops are half -formed vortex-rings, arrested by the 

 formation of a semi-permeable membrane ; but the explanation does 

 not seem to fit the blood-corpuscle. The cholesterin bodies in 

 Waymouth Reid's experiment are such as have a place of their own 

 among Lehmann's "fluid crystals "f; and it becomes at least con- 

 ceivable that obscure forces akin t6 those of crystalHsation may 

 be playing their part along with surface-energy in these strange but 

 famihar conformations. The case is a hard one in every way. 

 From the physiological point of view it is difficult and coinplex^ 

 enough. For the surface of the corpuscle is equivalent to a semi- 

 permeable membrane t, through which certain substances pass freely 

 but not others — for the most part anions and not cations §; and 

 accordingly we have here in life a steady state of osmotic inequih- 

 brium, of negative osmotic tension within, and to this comparatively 

 simple cause the imperfect distension of the corpus(5le may be due. 



* Proc. M.S. ;xn, pp. 251-257, 1862-63. 



t Cf. {int. al.) Lehmann, Ueber scheinbar lebende Kristalle und Myelinformen, 

 Arch.f. Entw. Mech. xx\^, p. 483, 1908; Ann. d. Physik, xliv, p. 969, iai4. 



X That no "true membrane" exists has long been known; cf. [int. al.) Rohring, 

 KoU. Chem. Beihefte, viii, pp. 337-398, 1916. On the other hand the surface of 

 the corpuscle is defined by a monolayer, and very probably by the still more stable 

 condition of two "interpenetrating" monolayers, a proteid and a lipoid. Cf. 

 Eric Ponder, Phys. Rev. xvi, p. 19, 1936; and on "interpenetration," Schulman 

 and Rideal in Proc. M.S. (B), cxxii, pp. 29-57, 1937. 



§ Cf. Hamburger, Z. f. physikal. Chem. lxix, p. 663, 1909; Pfluger's Archiv, 

 1902, p. 442; etc. 



