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



tion of the modified liquid from the cells of the adjacent tissues. In 

 the blood-vessels, the blood moves with such inconceivable rapidity, (the 

 whole mass of blood amounting, in man, to about 201bs., passing, as is at 

 present believed, over the entire sanguiferous circuit in two minutes,) 

 that there can be little opportunity for the completion of an action in 

 which the mingled liquids require to remain in contact for a length 

 of time. The liquid absorbed into the blood-vessels must be at once 

 hurried onward to the lungs, and other organs of sanguification, by 

 which it may be converted into the matter of the excretions ; or 

 possibly by the action of air, and admixture with fresh nutritious 

 matter, it may be reconverted into the serum of blood, which alone, 

 except in rare circumstances, we meet with in the blood-vessels. 

 There cannot, therefore, be any development of cell-germs, and cells 

 in the sanguiferous vessels, in animals whose blood circulates thus 

 rapidly ; that is, in any animals of the vertebrated class. But in all 

 such animals, there is provided a supplementary vascular system — 

 the system of lymphatic vessels, into which the serum of the blood 

 passes from the capillary blood-vessels by transudation, while the 

 modified serous liquid is supplied from the sources mentioned above — 

 in which the movement of the fluids is so slow, as to permit the com- 

 pletion of whatever reactions are required for the development of new 

 cell-germs ; and which is farther provided with plexuses and glands, 

 which seem still farther intended to facilitate those reactions. It is, 

 therefore, most probably in this system that all the corpuscles of the 

 blood originate : they enter the blood-vessels in a transparent form, 

 and in that state they contribute to the coagulation of the blood, and 

 to the development and renovation of the vascular tissues : while a 

 portion of them is, in all probability, converted into red corpuscles, by 

 a change in the colour and other qualities of the liquid contained 

 in their interior, analogous to the change by which we have seen the 

 same transparent vesicles converted into pus globules. 



7. In inflammation, also in blood-vessels. — In ordinary circum- 

 stances it is probable that no fibrinous corpuscles originate in the 

 sanguiferous system, on account of the rapidity of the motion of 

 the blood : but when that motion is obstructed, as in inflammation, 

 then the same reactions seem to go on in the capillary blood-vessels, 

 as in the cells of the inflamed part, where the organization of the 

 effused fluids is going on with vigour. Hence the production of the 

 buffy coat of the blood. In evidence of this local origin of the buffy 

 coat, I may mention the following observation which I have had 

 twice an opportunity of making. A person labouring under severe 

 whitlow was bled from one of the veins of the affected arm ; the blood, 

 in both instances, exhibited the buffy coat in the highest possible de- 

 gree. In one of the cases, the patient was simultaneously bled from 

 the other arm, and the blood thus obtained showed no buffy coat : but 



