322 



SCIENCE. 



[Vol. VII., No. 166 



that the fibrine filaments were formed by a disin- 

 tegration of the white corpuscles. On the other 

 hand, these corpuscles seem to be stable elements. 

 As a matter of fact, no observer has claimed ever 

 to have seen the actual change of a corpuscle into 

 fibrine. 



The process of coagulation can also be studied 

 in a fine capillary tube. The clot forms in the 

 centre, and the serain outside. The white cor- 

 puscles seem to be squeezed out of the clot, or to 

 migrate from it. 



Landois, whose observations were made some 

 ten years ago, thinks that the red corpuscles are 

 connected with the formation of fibrine. 



But the most interesting of all the problems is 

 the relation of the blood-plaques to this process of 

 coagulation. In blood drawn from the vessels we 

 see fine filaments shooting out radially from the 

 granule masses of Schultze. — those masses which 

 we have already learned are collections of the 

 blood-plaques. Ranvier, in 1873, regarded these as 

 the centres of fibrine formation. The fibrine cer- 

 tainly does stand in a thick, dense network about 

 these masses. In healthy blood, fibrine also ap- 

 pears entirely independent of the plaques. The 

 filaments are fine, and appear much like mar- 

 garine crystals. These filarpents may be especial- 

 ly dense near the plaques ; but any one can sat- 

 isfy himself, by examining the blood in the moist 

 chamber, that the fibrine forms independently of 

 them as well. If we pass a ligature through the 

 femoral vein of a dog, and allow it to remain for 

 five minutes, particularly if we have separated 

 the threads of the ligature, and then examine 

 it, we shall find it coated with blood-plaques. If 

 the blood of a dog is received into a cup, and 

 this is whipped with a brush of threads for five 

 minutes, we have the same aggregation of the 

 plaques upon the threads : some white corpuscles 

 will also be found, but the plaques are the strik- 

 ing feature. If these threads are dipped into a 

 solution containing a coagulable substance, clot- 

 ting will at once take place. The greater the num- 

 ber of blood-plaques, the denser and firmer will be 

 the clot. 



Still more instructive and interesting is the 

 study of thrombosis, or clotting in the blood-ves- 

 sels. If a dog is bled to death through a cut in 

 th<- femoral artery, and the vessel excised and 

 placed in osmic acid, and subsequently examined, 

 we shall find on the cut edges and in the lumen 

 of the vessel a finely granular material, and out- 

 side of this a darker mass composed of red cor- 

 puscles. The inner portion, the finely granular 

 material, however, which is in contact with the 

 elastic lamina, is composed of blood-plaques, and 

 not white corpuscles. These plaques are the first 



elements or factors in the formation of a throm- 

 bus. Eberth, in Yirchow's ' Archives,' has just 

 shown that the first elements to settle and to lodge 

 on lacerated vessels are blood-plaques. In all 

 white thrombi these plaques seem to make up 

 their bulk. If a needle is passed through a 

 blood-vessel in the omentum of a living animal, 

 the first elements which collect at the point of in- 

 jury are the blood-plaques, and a distinct white 

 thrombus is formed. These observations on the 

 relation of the plaques to coagulation have been 

 made by Bizzozero, Hayem, and Eberth. 



In the circulating blood the plaques keep with 

 the red corpuscles. If we examine a vessel of 

 the omentum of the rabbit or guinea-pig, we shall 

 see only a red streak, which occupies the central 

 part of the vessel. In the space between this and 

 the wall of the vessel, in the still layer as it is 

 called, we may occasionally see a few colorless 

 corpuscles. If the circulation now becomes 

 slower, we shall see the plaques in the still layer 

 with these colorless corpuscles. If atheromatous 

 ulcers of the aorta are examined, it will be found 

 that the material which has collected upon them 

 is made up of blood -plaques : the same is true of 

 the vegetations found upon the valves. While the 

 distinct plaque form is apparent in the superficial 

 parts of these structures, and the same is true of 

 white thrombi, the deeper parts are also plaques, 

 but in a granular state of disintegration. 



Eberth has shown, that while, in the rapid ly 

 circuiating blood, the corpuscles and plaques are 

 together, yet, if acid is placed on the edge of a 

 vessel or laceration, the plaques collect, and 

 form a definite aggregation or white thrombus. 

 We frequently find in autopsies atheromatous 

 ulcers or calcareous plates which have no thrombi : 

 in these cases, the circulation during life having 

 been rapid, the plaques remained central ; but, as 

 the current becomes slower, these plaques become 

 peripheral, and adhere to surfaces denuded of 

 endothelium, and thrombi result. 



LONDON LETTER. 



Important changes are in progress at Oxford 

 which will give the university a real faculty of 

 medicine. It has hitherto conducted medical 

 examinations for graduates in arts who h a v£ ob- 

 tained their professional education elsewhere, gen- 

 erally at one of the great London hospitals. But 

 in future Oxford men will be able to enter the 

 university as medical students, as has long been 

 the case at Cambridge. It will still be necessary 

 for them, however, to graduate in arts, which will 

 practically mean in the school of natural science, 

 before they can proceed to a medical degree ; and, 



