108 ANIMAL PHYSIOLOGY. 



In blood which has a tendency to " buff," the red corpuscles 

 are seen under the microscope to arrange themselves in 

 columns like rows of coin, their cohesive attraction one to 

 another being increased, or that between them and the 

 liquor sanguinis being diminished. The main function of the 

 red corpuscles is, as we shall find, to carry oxygen. 



77. The white or colourless corpuscles, also termed leucocytes, 

 are spherical in form, larger than the red, being, in man, about 

 g-oVo" inch in diameter, or more than that. They have a 

 turbid or mottled appearance, which, on addition of water, 

 disappears and discovers a nucleus. When coagulation is 

 retarded, and the red corpuscles sink, the white corpuscles 

 rise gradually to the top, showing that they are lighter than 

 the fluid part of the blood, while the red corpuscles are 

 heavier. Watching them as they circulate in the capillary 

 vessels of the web of a frog's foot, one may see that the white 

 corpuscles often show a tendency to adhere to the wall of 

 the vessel, while the red corpuscles keep in a stream in the 

 centre of it; and it has been proved by repeated observation 

 that white corpuscles are capable of making their way through 

 the capillary wall, which comes together again behind them 

 without apparent breach of continuity, while they pass on 

 into the tissue. It would appear that red corpuscles some- 

 times pass out in the same way; but the white have a much 

 greater tendency to escape, and after they have done so, no 

 line can be drawn between them and the other amoeboid 

 bodies, that is to say, the connective-tissue-corpuscles, for the 

 white corpuscles have amoeboid properties. Moreover, pus, 

 the matter thrown out in suppuration, consists of a fluid rich 

 in corpuscles, which cannot be separated by any line of dis- 

 tinction from white corpuscles ; and it is not yet settled to 

 what extent these consist of transuded white corpuscles, or 

 how far they are derived from processes of multiplication 

 among the connective-tissue-corpuscles. But whatever may 

 be the occasional functions of the white corpuscles exercised 

 by escaping into the tissues, they seem to have a much more 

 important purpose within the circulation, for it is probable 

 that the red corpuscles are formed from them by disappear- 

 ance of the nucleus and alteration of their contents. 



We shall find that the white corpuscles take origin in tho 



