6o 4 THE CHEMISTR Y OF THE URINE. 
the salts present, or, better still, if the salts be first reduced by dialysis. 
In some pathological conditions, and especially in cystitis, the amount may 
be so greatly increased that it separates as a viscid gelatinous precipitate. 
The mucoid appearance of the urinary nucleo-proteid led to its being long 
looked upon as mucin ; but it does not yield a reducing substance on 
hydrolysis, while, on the other hand, it is rich in phosphorus. Nevertheless, 
recent researches made upon large quantities of urine indicate that the 
precipitate given by acetic acid contains small quantities of ordinary 
mucin, or a phosphorus-free mucoid, as well as the nucleo-proteid. 1 
Apart from increase due to inflammatory conditions of the excretory 
tract, nucleo-proteid is said to be increased when the blood is excep- 
tionally rich in leucocytes (leukaemia). 2 
The question as to whether or not normal urine contains serum album in 
or scrum globulin offers a problem of the same order as that of physio- 
logical glycosuria, fully discussed on p. 608. The matter is, however, of 
less importance physiologically than is the latter question, as, all In nigh the 
evidence to hand points to the fact that if sufficient urine is employed these 
proteids may nearly always be separated in minimal traces, it by no means 
follows that they form part of the true excretion, for they may arise 
rather, like the nucleo-albumin, from the surface of the urinary tract. 
As to the cases when, in apparent health, there is such an increase of 
these proteids that their presence may be shown by the direct applica- 
tion of ordinary tests, we are met with the difficulty of having to define 
what is meant by " normal " urine. Such quantities may be present, 
for instance, after exceptionally severe exercise, as in the urine of soldiers 
after prolonged marching (Leube, Chateauburg) ; but it is not certain 
that the excretory mechanism is here working physiologically. 
When, as the effect of disease, the renal epithelium has undergone degenerat- 
ive changes, the presence of albumin in the urine is a common phenomenon ; 
one of the most familiar in pathology. Albuminuria may arise, too, from such 
alterations in the constitution of the blood as upset its normal relations to the 
renal cells ; this may be observed in anaemia, and as the effect of specific 
poisons. Again, it may follow disturbances of blood pressure in the renal 
vessels, even though these be unassociated with obvious changes in the 
excretory epithelium. Lastly, the albumin due to addition from the excretory 
tract, after the urine has left the kidneys, may pathologically reach a consider- 
able proportion. 
Under pathological conditions, also, the urine may come to contain 
albumoses and peptones. On the one hand, a so-called enterogenous peptonuria 
or albumosuria may occur, when, from degenerative changes in the gastro- 
intestinal walls (e.g. in carcinoma ventriculi or the ulcerative stage of enterica), 
the diffusible proteids reach the blood stream and thereupon are immediately 
eliminated by the kidneys. On the other hand, these substances may reach 
the blood stream from abscesses or other purulent collections where the tissue 
proteids have been hydrolysed by the growth of organisms. Whatever their 
origin (and it is sometimes not so clear as in the above groups of cases), the 
proteoses and peptones no sooner reach the blood than they are found in the 
urine. The older methods of investigation did not clearly distinguish between 
peptones and albumoses in the urine ; evidence is now accumulating to show 
that the latter are by far the more common. 
1 Cf. Malfatti, Wicn. Mm. Wchnschr., 1891, S. 433; also Morner, Skandin. Arch, 
f. Physiol., Leipzig, 1S95, S. 437. 
2 According to recent observations, the nucleo-proteid of urine is in some cases to be 
identified with Lilienfeld's " nucleohiston. " 
