CHANGES IN THE BLOOD. 89 



The most remarkable and perhaps the most important change 

 in the blood from defective excretion is that produced by- 

 arrested or deficient secretion of urine. In some experiments 

 performed by MM. Prevost and Dumas, who removed the kidneys 

 of dogs and cats, on the third day after the operation vomiting 

 came on, with diarrhoea of a copious brown liquid containing 

 ammonia, from transformation of the urea, eliminated from the 

 intestinal mucous membrane; fever, with heat sometimes as 

 high as 110°, sometimes as low as 92°; small and very frequent 

 pulse, laboured breathing, and death, from the fifth to the ninth 

 day. 



The post mortem appearances were, effusion of serum in the 

 brain, much mucus in the bronchial tubes, bilious fluid and 

 faeces in the intestines, an appearance of inflammation of the 

 liver, great contraction of the urinary bladder, the blood more 

 watery than usual, and containing urea ; five ounces of blood of 

 a dog yielding twenty grains of urea, and two ounces of cat's 

 blood ten grains. 



Defective secretion of urine, resulting from disease of the 

 kidneys, induces symptoms veiy similar to the above, differing 

 in degree and intensity according to the extent of the kidney 

 disease. Thus, in acute nephritis, or in rapid degeneration of 

 the kidneys, such an amount of urea and other effete urinary 

 matters may collect in the blood as to cause convulsions, 

 delirium, suffocative discharge of mucus from the bronchi, 

 diarrhoea, and serous effusion into the cavities and areolar tissue. 

 In subacute eases dropsy gradually ensues, the animal finally 

 becoming cachectic. All these effects may be traced to excre- 

 mentitious materials retained in the blood, especially urea, which 

 if in great amount acts as a narcotic poison, in smaller, as an 

 irritant, inducing inflammations in various membranes ; in the 

 horse, more especially in the membranes of the spinal cord, and 

 the neurilemma of the great nerves given off from the lumbo- 

 sacral plexus. 



TKANSFORMATION OF CHYLE AND OF THE TISSUES. 



The blood is kept in its normal or healthy condition by being 

 supplied with new elements derivable from the chyle, and by 

 having the products of the metamorphosis of the tissue and all 



