132 Dr. Buchanan on the Fibrin contained in the Animal Fluids. 



into a soft tremulous mass. The circumstance of their existing in the 

 liquid form distinguishes them from the solid fibrin of the muscles ; 

 while their spontaneous coagulability distinguishes them from albu- 

 men, which they closely resemble in all other respects, and which is 

 the chief animal principle found in the liquids in which they occur. 



II. ANIMAL FLUIDS CONTAINING FIBRIN. 



The principal animal fluids, which contain fibrin, are the Blood ; 

 the Lymph of the lymphatic vessels ; the Liquid of Blisters ; the 

 Coagulable Lymph, as it is usually called, met with under circum- 

 stances to be mentioned hereafter ; and lastly, the liquid of the pro- 

 perties of which I had the honour to read to the Society an account 

 in the year 1836, formed by the mixture of the scrum of the blood 

 with serum from cavities lined by serous membranes. 



III. — OBJECTS OF THIS MEMOIR. 



1. The fibrin, existing in these liquids, is usually held to exist in 

 them in a state of solution ; only passing to the solid state after they 

 are withdrawn from the body, during coagulation. I believe that 

 opinion to be erroneous : and the first object of this paper is to show, 

 that the fibrin does not exist in those liquids in the state of solution, 

 but exists while yet within the body, already solidified, and organized 

 in the form of granules and vesicles ; and that the process of coagula- 

 tion consists, simply, in the aggregation of these minute granules and 

 vesicles into a mass visible by the naked eye. This can only be 

 demonstrated by observing the coagulable liquids, under the micro- 

 scope, before, during, and after coagulation. 



2. The second object of this paper is to show, that the fibrinous 

 granules and vesicles contained in these coagulable liquids are 

 probably identical with the cell-germs and cells out of which, accord- 

 ing to the doctrine of Sclileiden and Schwann, all the tissues of the 

 body are developed. 



3. My third object is to show in what way the fibrinous granules 

 and vesicles are transformed into corpuscles of purulent matter ; and 

 that most probably they are converted also by an analogous process 

 into the red corpuscles of the blood. 



4. I shall last of all offer some conjectures as to the mode in which 

 these granules and vesicles originate in the serous fluids. 



I do not intend to discuss these subjects in the order in which they 

 are hero mentioned, but merely point them out as those, on which the 

 following observations upon the serous fluids containing fibrin are 

 chiefly intended to bear, and which I shall illustrate as opportunity 

 occurs. I begin with the fluid of blisters, as being that which is most 

 easily procured for observation, and which illustrates, in the most 

 striking manner, several of the subjects just enumerated. 



