306 
DR. HASSALL ON THE FREQUENT PRESENCE 
Since, however, normal urine-pigment very closely resembles haematin in its compo- 
sition, it is probable that in some cases indigo is formed from this pigment, altered 
or modified by disease. 
Professor Scherer* long since directed attention to the fact, that there is a close 
relation between the elementary composition of haematin and the several colouring 
matters of bile and urine, and he even hazards a conjecture that the two latter may 
be derived from the former. If we view the per-eentage composition of all these 
substances side by side, the following is the aspect they present : — 
White indigo 
(Crum). 
Haematin 
(Mulder). 
Bile-pigment 
(Scherer). 
Blue pigment 
of urine 
(Scherer). 
Brown pigment 
in disease. 
(Scherer). 
Brown pigment 
in health 
(Scherer). 
Carbon 
72-72 
70-49 
68-19 
66-99 
61-65 
58-43 
Hvdrojien 
4-54 
5-76 
7*47 
5-95 
5-60 
5-16 
Nitrogen 
10-60 
11-16 
7-07 
7-12 
7-29 
8-83 
Oxygen 
12-12 
12-59 
17-26 
19-94 
25-46 
27-58 
These numbers not only indicate the relation which exists between these substances, 
but they also show that there is a progressive removal of carbon by oxidation, and 
it is probable that the last of the series may represent the form in which, under 
ordinary circumstances, the haematin of the blood is removed from the body. 
To the above list of colouring matters, all intimately connected by their element- 
ary composition, may be added melanin, itself supposed to be derived from bile- 
pigment., and the composition of which, according to Scherer^, is as follows: — 
Melanin. 
Carbon 
.... 58-084 
Hydrogen .... 
.... 5-91/ 
Nitrogen .... 
.... 13-768 
Oxvgen 
.... 22-231 
100-000 
In the cases related in this paper, no reason exists for supposing that the indigo 
was derived from the colouring matter of bile, as in the urines in which the 
indigo was found, no traces of the presence of that secretion could be discovered, 
while in one only of three samples of urine examined highly charged with bile was 
any indigo found, and then but in small quantity. 
The colour and characters of the urines, as well as their chemical analysis, favour 
the supposition that the indigo, whether white or blue, was derived either from altered 
haematin or urine-pigment. The urines in which the indigo occurred in the largest 
quantities were pale, straw-coloured or light brown, often somewhat turbid, and 
appeared as though but imperfectly elaborated. 
* Ann. der Chem. und Pharm., bd. 57. s. 181-195. 
f Ibid. 40. s. 6. 
