Dr. Schunck on the Occurrence of Indigo-blue in Urine. 295 
a trace, and this took place when he was engaged in performing 
labour, unusual for him both in its nature and amount. In my 
own case, as well as that of my assistant, the amount varied 
most capriciously from a tolerable quantity to a mere trace, 
occasionally even none at all being obtained. 
I performed several experiments with different kinds of diet, 
in order to ascertain the effect on the amount of indigo-blue 
yielded by the urine. Only one experiment, however, led to 
any decisive result. Having selected an occasion when the 
night urine gave no indigo-blue, I took on the next night, 
before going to bed, a mixture of treacle and arrowroot boiled 
with water in as large a quantity as the Stomach could bear, 
aud the effect was that the urine of the following night gave 
a large quantity of indigo-blue. As, however, the same phe- 
nomenon was repeated for several succeeding nights without 
any additional quantity of food having been taken, it remained 
uncertain to what cause it was to be attributed, though a re- 
petition of the experiment on a second occasion gave the same 
result. 
I have hitherto not had an opportunity of examining many 
specimens of urine in disease. Of two samples of urine from 
patients with albuminaria, one gave a small quantity of indigo- 
blue, the other not a trace. Several specimens of diabetic 
urine yielded it. One of these, which I owed to the kindness 
of Dr. Browne of Manchester, gave a much larger quantity 
than I obtained from any other specimen of human urine. 
The urine of the horse and the cow, when tried in the same 
way as human urine, gave comparatively very large quantities 
of indigo-blue, especially that of the horse. 
I think it is highly improbable that the indigo-blue obtained 
in Hassall’s experiments was produced, as he supposes, by the 
action of oxygen on the urine. Its formation was without 
doubt due to the decomposition of the indigo-producing body 
induced by the fermentation of the urine, the indigo-blue at the 
moment of its formation dissolving in the fermenting alkaline 
liquid and producing a true indigo vat, from which it was 
gradually deposited by the action of the atmospheric oxygen. 
When small quantities of indigo-blue only are formed in any 
specimen of urine, fermentation is not in my opinion to be 
recommended as a means of detecting it. 
The occurrence of the indigo-producing body as an excretion, 
seems to me to be due to a disproportion between the oxygen 
absorbed by the system and the matter to be acted on by it, 
which again may be caused either by an excessive waste of the 
tissues or by an obstruction of the organs conveying oxygen, as 
the lungs and skin, or, as is probably the case in the majority 
