Symptoms of Decompression 681 



than half diminishes considerably the quantity of urea excreted 

 in 24 hours. Whatever may be the various causes of error inherent 

 in the experimental procedures, the exact agreement in direction, 

 if not in absolute value, of the variations in all the experiments 

 established satisfactorily a degree of certainty. 



This decrease has not been proportional to the decrease in pres- 

 sure; it has varied with circumstances generally unknown; its 

 maximum was 50.8 per cent in Experiment CCXL. 



In examining the record of these experiments, we notice that in 

 number CCXLII, the decrease in urea was not seen on the day of 

 the decompression, (23.4 gm. to 23.5 gm.) but the next day (17.3 

 gm.) ; the day after, normalcy was almost established (21.8 gm.) . 

 In another case, Exp. CCXLI, on the day after the stay in decom- 

 pressed air, the quantity of urea yielded was much increased, and 

 rose considerably above the original figure, under normal pressure. 

 These are questions of detail for the study of which we should be 

 forced to increase the number of experiments, taking as subject 

 man, in whom uniformity of diet, uniformity of movement, etc., can 

 be more exactly obtained. 



Disregarding these secondary points, it is established that at 

 low pressures the decrease in activity of chemical phenomena af- 

 fects not only those which produce carbonic acid, but also those 

 which cause the excretion of urea. The whole combination of 

 intra-organic acts of oxidation is therefore considerably decreased 

 when the air is sufficiently expanded. 



We must note that uric acid did not seem to be increased in the 

 urine of the dogs, when the urea diminished; at least we did not 

 note any precipitate, either spontaneous or following the acidifica- 

 tion of the urine. This fact supports many others in showing that 

 urea is not a product of the oxidation of uric acid, but that these 

 two substances proceed from different chemical transformations. 



3. Sugar of the liver and of the blood, glycosuria. I have re- 

 peatedly established the presence of sugar in the urine of animals 

 kept for several hours at low pressures. But the phenomenon 

 always appeared in an irregular manner, so that I have not been 

 able to reproduce it at will in comparable experiments. 



On the other hand, when the decompression is great and acts 

 for a long time, sugar is more or less decreased in the liver; it may 

 even wholly disappear. Example: 



Experiment CCXLIII. August 1. Rat, kept in a large bell, with air 

 renewed from time to time, at a pressure oscillating between 30 and 

 40 cm., from 1:10 to 6:45. 



