OF THE 'BLOOD. 223 



After this experiment has been made on the blood of such 

 animals as have large vesicles, it may be made on human blood, 

 where the water will be found to have the same effect ; the 

 vesicles will become spherical, the diameters of these spheres 

 will be less than the largest diameter of the vesicle in its flat 

 state. 



It is remarkable that more water is in general required to 

 produce this change on the vesicles of the human blood than 

 on those of frogs, or other amphibious animals ; and those of 



matter by repeated additions of water, the membranous base of the disc 

 is left pale, pellucid, thin, flat, about two thirds as large as the un- 

 changed red corpuscle, and often not visible without the aid of sublimate 

 or iodine. This colourless base has been described by Sir Everard 

 Home,* and by Dr. Rees and Mr. Lane, 5 as the nucleus of the red 

 corpuscle of man. When the corpuscle of the oviparous vertebrata is 

 washed with water, the envelope and nucleus both remain, perfectly dis- 

 tinct from each other, the nucleus being the thickest, much the smallest, 

 and very plain. If a layer of the corpuscles of mammalia be quickly 

 dried on glass, preserving their form, and then moistened by the breath, 

 the envelopes will become pale and pellucid ; but no nuclei appear. 

 Treat some corpuscles, no matter how minute they may be, of an 

 oviparous vertebrate animal in the same way, and the nuclei will be 

 seen through the envelopes as distinctly as any microscopic object can 

 well be. The shape of the nucleus is described in Note cv ; and more 

 particular details on all these points, with illustrative figures, will be 

 found in Wagner's ' Physiology,' translated by Dr. Willis, pp. 239-41 ; 

 and in the 'Lond. and Edin. Phil. Mag/ Aug. 1842, pp. 107 et seq. 



Granular spots, either circular or variable in form and size, often 

 occur in the blood-disc of a mammal in consequence of a puckering of 

 the envelope, shrinking in one part and swelling in another, from a 

 variation of the contents of the corpuscle. Similar appearances, some 

 of which look very like a nucleus, may also be observed by adding 

 dilute muriatic acid or saline solutions to the blood under the microscope : 

 see Note cxi. Some of the deviations from the regular appearance of 

 the corpuscles are noticed in Notes cvi, ex, and cxv; and in the Appendix 

 to the English edition of Gerber's 'Anatomy,' pp. 9-11. Of the con- 

 tents of the corpuscles, De Blainville c observes, "Les globules seraient 

 formes d'une petite vessie pleine d'une fluide analogue au vehicule, et 

 dans lequel se trouverait la matiere colorante ; et chacun de ces globules 

 en renfermerait d'autres plus petits, quoique de mme structure ; c'est 

 P opinion de M. Raspail, qui compare alors les globules du sang a ceux 

 de la fecule de pomme de terre." See the interesting observations of 

 Mr. John Queckett on the blood-discs and their contents. d 



:| Pliil. Trans. 1818, pp. 173-74. c Cours de Physiologic gen. et comparee, 



' Guy's Hospital Reports, 1841, vol. vi, torn, i, p. 209, 8vo, Paris, 1829. 



p. 383. '' Microsc. Journ. p. 67, 8vo, Lond. 1841. 



