91 



canals. Of this appearance an exact representation is given in an- 

 nexed drawings. It explains, says the author, the important change 

 which the blood undergoes after extravasation in living animals, and 

 leaves no difficulty in accounting for its becoming vascular by re- 

 ceiving the red blood into the tubes thus prepared. 



The author concludes his lecture by acknowledging his obligations 

 to the unexampled zeal and exertions of the President in promoting 

 and facilitating scientific pursuits. It was under his encouragement, 

 and in compliance with his wishes, that Mr. Bauer, laying aside for 

 the time his customary researches in vegetable anatomy, turned his 

 attention to the subject of the present communication, and assisted 

 in bringing those appearances to light, which, without his aid, must 

 still have remained in obscurity. 



Some Additions to the Croonian Lecture, on the Changes the Blood un- 

 dergoes in the Act of Coagulation. By Sir Everard Home, Bart. 

 V.P.R.S. Read March 5, 1818. [Phil. Trans. 1818, p. 185.] 



The object of this paper is to furnish a more correct measurement 

 of the globules of the blood than that formerly offered, and to esta- 

 blish, by additional facts, the author's opinion respecting the forma- 

 tion of tubes during the coagulation of the blood. The diameter of 

 a globule of blood, as ascertained by Mr. Bauer, was considered as 

 .nrWth of an inch ; whereas it appeared, from the more correct in- 

 vestigations of Capt. Kater, to be only -ruWth. 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 re- 

 admission 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 know- 

 ing 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 



