Some additions to the croonian lecture, on the changes the blood un dergoes in the act of coagulation

The object of this paper is to furnish a more correct measurement of the globules of the blood than that formerly offered, and to establish, by additional facts, the author’s opinion respecting the formation of tubes during the coagulation of the blood. The diameter of a globule of blood, as ascertained by Mr. Bauer, was considered as 1/2000th 0f an inch ; whereas it appeared, from the more correct investigations of Capt. Kater, to be only 1/5000th. To show that the extraction of air was the cause of the tubular structure observed in coagulated blood, the author placed a portion of recently drawn blood under the receiver of an air-pump; and when it had coagulated, the air having been thus previously removed, no tubular appearance was manifested. In a portion of the same blood, coagulated previous to the exhaustion of the air, the tubuli were beautifully distinct. The author succeeded in injecting these tubuli by placing some fine size injection upon a piece of coagulum, and putting it under the receiver of the air-pump : during exhaustion the air escaped, and on its readmission into the receiver the injection was forced into the tubular structure. Sir Everard next proves that coagula of blood, formed in the abdomen, may be injected from the contiguous vessels; and on microscopic examination it is shown, that the small arteries of the peritoneum enter the tubuli of the coagulum, and that the latter form vessels larger than the former ; and that there are lateral points of communication between the tubuli and arteries. Sir Everard next relates some experiments upon pus similar to those upon the blood,— a fact, he observes, of much importance in practical surgery; for knowing that inspissated pus becomes vascular similar to coagulated blood, we have arrived at the principle on which granulations are formed, and whence they observe their inherent power of contraction. We can also account for the advantage of compressing the surface of sores; since by that means, continues the author, all superfluous pus is removed, leaving only enough for inspissation, in which state it becomes tubular, afterwards vascular, and then takes the form of healthy granulations.