1888 - 89 .] Dr Haycraft on Chromatology of the Bile. 191 
Changes, not very dissimilar in their nature, occur when blood is 
received directly into a sterilised tube from an artery. In this case 
the oxyhsemoglobin is reduced, and remains for years without under- 
going further change. In the sterilised tubes filled with bile the 
change in colour seemed to be influenced in the thick mucus of the 
bladder, for those that contained most mucus invariably became 
brown before those that contained less mucus. 
It will be seen, however, by the results of the next two experi- 
ments, that reduction occurs quite readily in the absence of bladder 
mucus. The two experiments were unfortunately performed, the 
first in dull cold weather, and the second in warm bright weather, 
so that they cannot be very rigidly compared. One can conclude, 
however, from the general results obtained, that thick bladder mucus 
assists the reduction, although its presence is not essential. 
Experiment VI . — Exhausted and sterilised tubes were filled with 
bile drawn directly from the hepatic duct of a freshly killed ox. 
Reduction took place in three days. 
Experiment VII . — In order to ascertain whether reduction would 
take place in bile absolutely free from mucus, this substance was 
precipitated by means of alcohol. The filtrate subsequent to the 
separation of the mucus was evaporated over a water-bath until the 
alcohol was expelled. The reduction took place, however, in two 
days ; the weather was hot and bright. 
The last experiments were made during hot midsummer weather, 
and it was noticed that, while in all cases reduction took place with 
rapidity, this was especially the case in the tubes most exposed to 
light. In the following experiments the action of light was more 
fully investigated. 
Experiment VIII. — (a) Bile within test-tubes exposed to light was 
reduced in twenty-four hours, and after a week failed to 
give Gmelin’s test ; weather hot and bright. Other portions 
of the same bile in a dark metal chamber were reduced in 
three days. 
( b ) Bile boiled in plugged tubes and exposed to light was reduced 
in twenty-eight hours. A portion treated in a similar way, 
but placed within the dark chamber, still preserved a trace 
of the original green colour for seventeen days. 
(c) Bile within the exhausted and sterilised tubes was reduced 
