HORSE MANAGEMENT, ETC. 403 



"The weight of an animal being ascertained to be seventy- 

 nine Dounds, a puncture was made with a lancet into the jugular, 

 from which the blood flowed in a very free stream, and was col- 

 lected. The vein having ceased to bleed, the caroted artery of 

 the same side was divided, but no blood came from it. In a few 

 oeconds afterward the animal was dead. The weight of the car- 

 cass was found to be seventy-three and one half pounds ; conse- 

 quently, the animal had sustained a loss of 5.12 pounds, precisely 

 the measure of the blood drawn. 



It appears, therefore, from this experiment, that an animal will 

 lose one-fifteenth of its weight of blood ere it dies, although a less 

 quantity may so far debilitate the vital powers as to be, though 

 less suddenly, equally fatal. In the human subject, the quantity 

 of blood has been computed at about one-eighth part of the weight 

 of the body ; and as such an opinion has been broached from the 

 results of experiments on quadrupeds, we may fairly take that to 

 be about the proportion of it in the horse ; so that if we estimate 

 the weight of a common-sized horse at about 12 cwt., the whole 

 quantity of blood will amount to 84 quarts, or 168 pounds, of 

 which about 45 quarts, or 90 pounds, will flow from the jugulai 

 vein prior to death, though the loss of a much smaller quantity 

 will sometimes deprive the animal of life." 



The Rapidity of the Circulation. 



In 1827, Hering,* a German physiologist, performed the ex- 

 periment of injecting into the jugular vein of a dog a harmless 

 substance, which could be easily recognized by its chemical reac- 

 tions, and noted the time which elapsed before it could be de- 

 lected in the vein of the opposite side. This gave the first correct 

 idea of the rapidity of the circulation ; for though the older phys- 

 iologists had studied the subject, their estimates were founded on 

 calculations which had no accurate basis, and gave very different 

 lesults. The experiment of Hering is often roughly performed 

 as a physiological demonstration, and we have thus had frequent 

 occasion, in a general way, to verify its accuracy. If, for ex- 

 ample, we expose both jugulars of a dog, inject into one a solution 

 of ferro-eyanide of potassium in water, and draw a specimen of 



Milne-Edwarda. 



