SIMPLE ISOLATED CELLS; RED BLOOD-CORPUSCLES. 



125 



the cell and of the surrounding fluids may direct. Thus, if the Red corpus- 

 cles be treated with water, there is a passage of that liquid into the cell ; the 

 disc becomes first flat, and then double-convex, so that the central spot disap- 

 pears ; and by a continuance of the same process, at last becomes globular, 

 and finally bursts, the cell-wall giving way, and allowing the diffusion of the 

 contents through the surrounding liquid. On the other hand, when the Red 

 corpuscles are treated with a thick syrup or solution of albumen, 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. 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.* We hence see the necessity, in examining the Blood 

 microscopically, for employing a fluid for its dilution, that shall be as nearly 

 as possible of the same character with ordinary liquor sanguinis.t 



144. Microscopic observers have been much divided upon the question, 

 whether or not the Red corpuscles of the Blood of Man and other Mammalia 

 contain a nucleus. There seems every probability from analogy, that a nu- 

 cleus exists in them, as it does in the red corpuscles of all other animals ; 

 but it cannot be brought into view by any of the ordinary methods, which 

 render it distinctly visible in the oval blood-discs of Oviparous Vertebrata ; 

 and of late the general opinion has been, that nothing resembling their nuclei 

 could be present in the blood-discs of Man and Mammalia. Dr. G. O. Rees 

 states, however, that, by carefully examining the ruptured cell-walls, which 

 fall to the bottom of the water when red corpuscles have been diffused 

 through it, he could distinguish appearances on them, that indicated the ex- 

 istence of nuclei ; although they escape observation when within the corpus- 

 cles themselves, on account of their high refractive power. He describes 

 them as being circular and flattened, like the Red corpuscles themselves ; and 

 as about two-thirds of their diameter. 



145. In all Oviparous Vertebrata, without any known exception, the red 

 corpuscles are oval, the proportion between their long and short diameters, 

 however, being much subject to varia- 

 tion ; and their nuclei may always be Fig. 28. 



brought into view, by treatment with 

 acetic acid, when not at first visible. In 

 the red particles of the Frog, which are 

 far larger than those of Man, a nucleus 

 can be observed to project somewhat 

 from the central portion of the oval, 

 even during their circulation ; and it 

 is rendered extremely distinct by the 

 action of acetic acid ; this renders the 

 remainder of the particle extremely 

 transparent, whilst it gives increased 

 opacity to the nucleus, which is then 

 seen to consist of a granular substance. 

 In the still larger blood-disc of the Proteus and Siren, this appearance is yet 



See Dr. G. 0. Rees' Gulstonian Lectures, for 1845. 



\ 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 ; as the serum of one Mammal reacts injuriously on the blood of another. 

 See Philos. Magaz., Jan. and Feb. 1840. 



11* 



Panicles of Frog's blood; 1, 1, their flattened 

 face ; 2, particle turned nearly edgeways ; 3, 

 lymph-globule; 4, blood-corpuscles altered by di- 

 lute acetic acid. Magnified 500 diameters. 



