Licence: Public Domain Mark
Credit: A text book of physiology / by William Rutherford. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
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![the red corpuscles and of muscle notably differ from those of other tissues in the fact that sodium salts are almost entirely replaced by tliose of potassium. The principal gas of the corpuscles is oxygen, but they also contain a trace of carbonic acid. The quantities of the chief constituents are as follows:—Water, 56 '5 per cent. Solids, 43'5. 100 parts of the dried organic matter of the corpuscles of dog's blood (Jiidell, Op. 21, Heft iii. 386) contain hajmoglobin, 86-5. Other albuminoid matters, 12-55 Lecithin, 0'59. Cholesterin, 0-36. Development of Blood-Corpuscles.—In the embryo the blood- corpuscles are developed exclusively in the middle layer of the germinal membrane. In the chicle, according to Klein {Ojx 40, year 1871), the blood-cor- puscles are developed from the nucleated protoplasts of the mesoblast in two ways—(I) The nuclei of certain protoplasts multiply, and the poly- nucleated mass differentiates into a central mass of nucleated pro- toplasts—young blood-corpus- cles (d in large central mother- cell of Fig. 23) ; while the outer part becomes an envelope —the wall of a future capillary —consisting of a nucleated layer of protoplasm (h in same cell). The protoplasmic wall of the capillary grows outwards at various points {B^, and joins processes (/) from neighbouring cells. The processes, at first solid, become hollow, the blood- plasma appears between the blood-corpuscles, and thus a system of capillaries and vascular contents arise. (2) Another and perhaps more frequent mode of formation consists in an early vacuolation of the polynucleated protoplasmic mass (B). The vacuole (a) is the interior of a future vessel, and is filled with blood-plasma. The nuclei in the vascular wall proliferate, and with some of the i)rotoplasm grow as buds towards the interior of the vessel, drop off, and become blood-corpuscles (d). Wlaile this is going on, the protoplasmic wall of the mother-cell buds outwards, branches, joins with the processes of its neigh- bours, and forms a system of capillaries in the way already described, its polynucleated protoplasm becoming a series of epithelial plates, that con- stitute the wall of the capillaries. Klein asserts that the blood-pigment appears in the protoplasm around the nuclei of the coloured corpuscles ; but Balfour (Op. 8, xiii. p. 280) maintains that the perinuclear pigmented parts of the blood-corpuscle are formed from the nuclei of the parent cell, while the nucleoli of the latter become the nuclei of the blood-corpuscles. Blood-vessels and also blood-corpuscles may originate in a manner similar to the above in inflamed tissues (Strieker, 0]}. 38, iii. p. 542). After the development of blood-corpuscles and blood-vessels the former Fig. 23. Devolopmont of blood-vessels (I) and blood uorpusclos (t?) in mesoblast of chick. See text. (Klein.)](https://iiif.wellcomecollection.org/image/b21981747_0074.jp2/full/800%2C/0/default.jpg)
