412 PHYSIOLOGY CHAP. 



According to the average of Bouchard's results, the urotoxic 

 coefficient of man under normal conditions is equal to 0'464, and 

 varies within narrow limits. In pathological conditions it rarely 

 exceeds 2, and rarely falls below 010. 



The following was Bouchard's method of determining the urotoxic 

 coefficient of the urine : say that in a healthy man of 60 kilns, body-weight 

 1200 c.c. urine are excreted in the 24 hours. If 50 c.c. of this urine per kilo. 

 of the animal (rabbit) kill it, i.e. contain 1 urotoxia, then the 1200 c.c. urine 

 must contain 24 urotoxias. In effect, 50 : 1 :: 1200 : x, therefore 



1200 

 X=: -50- 24 ' 



If 60 kilos, of man produce 24 urotoxias per diem, 1 kilo, must produce 



24 



v^r =0'4 urotoxias ; 



0'4 is therefore the normal urotoxic coefficient. 



On the hypothesis that susceptibility to urinary poisons is the same for 

 man as for rabbit, the amount of urine necessary to kill the man by whom 

 it lias been excreted can be calculated. We have therefore the following 

 proportion : 24 : 1200 : : 60 : x, whence it results that 



i.e. 3 litres of urine will kill a man of 60 kilos, body-weight who daily 

 excretes 24 urotoxias, viz. the urine passed in two days and eight hours. 



The toxicity of normal urine is affected by cerebral activity, 

 muscular activity, sleep, nutrition, etc. The variations involve not 

 only the amount but also the nature of the urinary toxins. The 

 urine of sleep, although denser and richer in solid matters, is 

 nearly always, given the same volume and time of secretion, less 

 toxic than the urine of waking. During sleep, according to 

 Bouchard, man elaborates 2-4 times less poison than during the 

 corresponding period of cerebral activity. Further, the urine of 

 sleep produces convulsions, while that of waking is narcotic. The 

 body must, therefore, when awake manufacture substances which, 

 on their accumulation, induce sleep ; during sleep, on the contrary, 

 it accumulates such as discharge muscular twitches and provoke 

 awakening. On mixing the urine of sleep with that of waking, 

 the result is not average toxicity, but a toxicity lower than that 

 of the less toxic urine. 



Muscular work, far from augmenting the toxicity of urine, 

 diminishes it by one -third, and this diminution persists for 

 several hours after the muscular activity ceases. According to 

 Bouchard these facts support the conjecture that the toxicity of 

 the urine depends not on its mineral constituents, which certainly 

 do not diminish with movement, but rather on the incompletely 

 oxidised organic substances, the toxicity of which diminishes in 

 proportion as they become oxidised. 



