On the containing-texture of the blood / by William Addison.

Date:
[1850?]
Catalogue details

Licence: Public Domain Mark

Credit: On the containing-texture of the blood / by William Addison. 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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    tONTAlNING-TEXTURE OF THE BLOOD By WILLIAM ADDISON, M.D. F.R.S. F.L.S. From the London Medical Gazette. The relations which have been esta- blished between the process of repair and inflammation, and between these and natural growth, have invested em- bryological researches with a new inte- rest, especially with reference to the development, properties, and transfor- mations of vascular tissue, or, as it may be more suggestively expressed, the containing-texiure of the blood. In the primitive trace of growth in the em- bryo, sentient and motor forms (spinal cord, cerebral ganglia, and heart) are the first moulded, and visible, through a lens, in the incubated egg of the common fowl within the space of forty hours. At this early period there is neither a blood-circulation nor blood vessels. Blood is first seen, not in the embryo-body itself, but in the vascular area, where it primarily appears in irregular, and apparently unconnected red points or blotches, which, when examined writh a microscope, are ob- served to be groups of red cells situated amongst the other cells of this embryo nic appendage, and no special limiting or boundary tissue can be distinguished. A growth advances, the amount of blood increases, circulation begins, and the coats of the vessels then become recognisable as a distinct form of tissue interposed between the blood-current and the fixed and more solid portions of the structure. This constitutes the coats of the arteries, veins, and capil- laries, as distinguished from the parti- cular substances of the various organs through which blood is distributed, and is, at first, in accordance with the universal law of growth, a corpuscular, and subsequently a fibrous tissue, in- creasing gradually in thickness and strength, in the arteries and veins, in pro- portion to the increase and volume of the blood conveyed; but in the capilla- ries remaining, as at first, exceedingly thin and transparent. These facts are, we believe, not dis- puted, and they are here briefly nar- rated in order to state the case:—That, in original growth, forms of sentient and motor tissue precede the circula- tion of the blood; that the circulation of blood precedes the formation of the special coats of the blood-vessels; and that these are at first a corpuscular, and then a fibrous texture. Experiment 1.—Having opened the shell of an egg after forty or forty-four hours’ incubation,—some eggs being earlier than others,—divide the yolk membrane with a pair of scissors all round, just outside the vascular area ; then sink the egg slowly in a vessel of water, and the separated portion, which includes the vascular area, area pellu- cida, and the embryo, will float at the surface, and may be removed upon a slip of glass for microscopical inspec- tion, either as an opaque, or as a trans- parent object Blood is seen in the vas- cular area, in apparently unconnected, irregular, pale red spots, which are larger and more numerous towards the outer circumference than towards the inner margin, where the area vasculosa bounds the area pellucida. The area pellucida is formed by a thick gela- tinous sort of membrane, in the centre