On the development of the blood and blood-vessels, being the prize essay for 1854 of the Edinburgh Harveian Society / by James Drummond, M.D.

Drummond, James

Date:: [1854]

Credit: On the development of the blood and blood-vessels, being the prize essay for 1854 of the Edinburgh Harveian Society / by James Drummond, M.D. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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$Axsnch the same cliemical constitutioii as tlie:*erum of the blood. .It •iorms the blastema from which the cells of the ovum are developed, •and from ^^-hich ihey derive the material for their nourishment. It performs the same ofQce to the cells of the ovum which the serum ■of-- the blood performs to the different tissues of the perfect animal. The serum of the blood in very young embryos appears to > onsist merely of a portion of this fluid, just as the embryonic corpuscles con- stitute the first blood corpuscles, so also the serum of the blood-is at first formed of a portion of the fluid in which the embryonic cor])uscies float. According to Prevost and Lebert, it is probable that the Jis- ap^'jearance of the granules from the embryonic corpuscles is due *•> a-iiquefaction of the same, while the fluid so formed passes tlirougl; the cell wall by a process of exosmosls, and constitutes the senim 'of the blood. It seems, however, more probable that the granules in question go to the formation of the ha3matine. In the mammal the serum must be chiefly derived from the maternal system by ab- soi-ption thi'ough the medium of the placenta. As soon as th( lymphatic system is formed, the serum of the blood must in the frog, at least, be chiefly-derived from this source. i;; -. Zimmerman and others, regarding the fibrine as not intended to afford nourishment to the tissues, but as a product of their effete matter, have stated that the blood of the foetus contains no fibrine. In the chick, however, on the thii'd or fifth day of its development, I have sometimes removed from the heart a small mass of coagulated blood. In the mammalian foetus pretty far advanced, I have also observed that when the blood taken from the umbilical vessels was allowed to stand for a short time a coagulum formed. This, how- ■'ever, is much looser and smaller compared with the quantity of blood than in the adult, and in the vessels and heart of the foetus I have not observed firm coagula, such as occur after death in those of the perfect animal. The quantity of fibrine then in the blood of the foetus appears to be much smaller than that in the blood of the adult, and in very young foetuses it probably does not exist at ail. The presence of fibrine in the blood of the foetus cannot be re- garded as' an objection to the views held by Zimmerman, Hughes Bennett, and others, in regard to the origin of this suhstancej inas- much as we must expect that the process of disintegration goes on during embryonic life, in the feame manner as in the growing animal, though perhaps in a less degree, and as a result of this process fibrine may be formed, though in smaller quantity than in the blood of the animal after birth. SEC. ai.-ui)itrEE0PMBNa?r)A3rij STRUCTURE OF THE BLOOD-VESSELS. 'i !'..V'=,' •) i:'l(: :\:.// y;:iv,-'i, t]: In what follows on the development and structure of the foetal blood-vessels, the same alTtingement will be observed as in the pre- ceding section. Thc^ mode of formation and Structure of the greater$