32 



Mr. Andrews on the Changes of the 



[Jan. 



country to bleed these animals several times before they are 

 slaughtered, I availed myself of this circumstance to pro- 

 cure suitable portions of blood . The animal is bled from a 

 large orifice in the jugular vein, till symptoms of syncope 

 appear, and the operation is in general repeated at intervals 

 of twenty- four hours. It is once fed between each operation 

 upon a mixture of meal and water, but this is often omitted 

 before the last bleeding. 



The appearance of the blood becomes greatly altered by 

 the successive abstractions; the crassamentum is at first 

 very large, and a portion of the red globules are unattached 

 to it, but it progressively diminishes in bulk while its con- 

 sistency increases, till upon the fourth bleeding it appears a 

 small contracted ball immersed in a large quantity of serum, 

 adhering to the stopper of the vessel in which it is contained, 

 and presenting on its external surface an exact cast of the 

 interior of the vessel. 



The following analyses were performed by the same me- 

 thod that I formerly employed in a set of experiments on 

 the blood of Cholera patients, which were published in the 

 Philosophical Magazine for September 1832. They are 

 nearly all a mean of two separate analyses which seldom 

 differed from each other more than 0*5 per cent. 



A calf was bled four times ; between the first and second 

 bleedings a week elapsed, but the rest took place at intervals 

 of twenty-four hours, and the animal was fed between each 

 operation. The composition of the serum and blood at each 

 bleeding is exhibited in the following tables : 



SERUM, 



Water .... 

 Albumen and Salts 



Water 



Albumen and Salts. 

 Red globules & fibrin 



