158 OF THE BLOOD. 



the laws of Endosmose, either inwards or outwards, as the relative density of the 



contents of the cell and of the surrounding 



Fig. 11. fluid may direct. Thus, if the Red Cor- 



puscles be treated with water, or with a 

 solution of sugar, albumen, or salt, which 

 is of less density than the liquor sanguinis, 

 there is a passage of this liquid into the 

 cell ; the disk first becomes flat, and then 

 double convex, so that the central spot 

 disappears; and by a continuance of the 

 same process, it at last becomes globular, 

 and finally bursts, the cell-wall giving 

 way, and allowing the diffusion of its con- 

 Red Corpuscles of Human Blood; represented ^^ through the Surrounding liquid. If, 

 at a, as they are seen when rather beyond the , , , , , -p i /~i i 



focus of the Microscope; and at6,as they appear the Other hand the Red Corpuscles 

 when within the focus. Magnified 400 diameters. D6 treated With a thlCK Syrup, Or With a 



solution of albumen or of salt, they will 



be more or less completely emptied, and caused to assume a shrunken appear- 

 ance; the first effect of the process being to increase the concavity, and to 

 render the central spot more distinct. 1 It is probable that the Blood-corpuscles, 

 even whilst they are circulating in the living vessels, are liable to alterations of 

 this kind, from variations in the density of the fluid in which they float ; and 

 that such alterations may be constantly connected with certain disordered states 

 of the system. 3 Thus, even without such an alteration in the Blood as would 

 constitute disease, its proportion of water may be temporarily so much dimin- 

 ished by diuresis or excessive perspiration, unbalanced by a corresponding 

 ingestion of liquid, that the corpuscles may be made to present a granulated 

 edge ; which is rendered smooth again by the dilution of the liquor sanguinis 

 with water. We hence see the necessity, in examining the Blood microscopic- 

 ally, for employing a fluid for its dilution, that shall be as nearly as possible of 

 the same character with its ordinary "liquor sanguinis/' 3 Microscopic observers 

 were formerly divided upon the question, whether or not the Red Corpuscles of 

 the blood of Man and other Mammalia contain a nucleus; but of late there has 

 been a general accordance in the statement that, in the fully-formed disk, no 

 nucleus is discoverable, although it may be sometimes seen in cells whose 

 formation seems to be incomplete ; and from the observations of Mr. Paget and 

 of Mr. Wharton Jones, it would seem that we are to regard the absence of 

 nucleus as marking a more advanced stage of development, than that which 

 obtains in the blood-corpuscles of the lower Vertebrata, or in the early condition 

 of those of the highest ( 150, 151). 



1 A large number of experiments of this kind were made, and their results accurately 

 recorded, by Hewson (see his "Inquiry into the Properties of the Blood," 1782, and his 

 " Description of the Red Particles of the Blood," 1788), who drew from them the inference 

 of the vesicular character of the Red Corpuscles. These experiments were repeated and 

 varied by other physiologists, of whose results a table has been given by Mr. Ancell ("Lec- 

 tures on the Physiology and Pathology of the Blood," in the " Lancet," Dec. 7, 1839) ; but 

 the facts stated in the text are those of most importance, and their true rationale seems to 

 have been first given by Dr. G. 0. Rees and Mr. S. Lane. (See their Memoir "On the 

 Structure of the Blood-Corpuscle," in "Guy's Hospital Reports," No. xiii.) 



2 See Dr. G. 0. Rees's Gulstonian Lectures, in the " Medical Gazette" for 1845. 



3 By Wagner, the filtered serum of frog's blood is recommended for this purpose. 

 Weak solutions of salt or sugar, and urine, answer tolerably well; but Mr. Gulliver 

 remarks that all addition must be avoided, when it is intended to measure the corpuscles, 

 or to ascertain their true forms ; since even the serum of one Mammal reacts injuriously 

 on the blood of another. See "Philos. Magazine," Jan. and Feb. 1840. 



