1897.] Scope and Present Position of Biochemistry. 273 
chemical. We are now familiar with the progressive differenti- 
ation of organs from the egg, but of the nature of the chemical 
differentiation which this structural differentiation implies 
little is as yet known. Whether the chromatins of the cells 
derived from the egg are different from that of the egg-cell, 
and in what way, is a question of theoretical interest to be 
answered definitely only by biochemical research. The de- 
termination of the chemical nature of the substance causing 
cell division, karyokinesis, of the substances formed, and of 
the nature of the changes undergone, is essential to the under- 
standing of this process. The answer to these questions may 
be of value in the explanation of tumors and other pathologi- 
cal growths involving karyokinesis. | 
Biochemistry has perhaps its chief practical worth in medi- 
cine. The physician it serves not only indirectly through the 
solution of physiological and bacteriological problems, but 
directly in testing the action of drugs and diets upon metabol- 
ism, and in the careful study of the urine and blood in health 
and disease. The physician is thus given an accurate means 
of diagnosis in certain diseases. An interesting result accom- 
plished recently in this direction has been the discovery of the 
origin of uric acid, a substance of considerable pathological 
interest, in the chromatin of the cell-nuclei, and thereby a pos- 
sible explanation is given of the action of quinine, antipyrin, 
and antifebrin, in decreasing the secretion of this substance. 
Another practical biochemical problem important in medi- 
cine is the isolation from glands and other organs of their so- 
called “internal” secretions already mentioned. Hitherto, in 
treating myxcedema, goitre, or Addison’s disease, by the so- 
called extract therapie, physicians have used either the whole 
substance of the thyroid, or thymus glands and the suprarenal 
capsules, or extracts of these organs—a process which intro- 
duces useless as well as healing matter. It would be advanta- 
geous to use the pure remedial substance alone. In one of these 
organs this is now possible, two biochemists having recently 
isolated the healing substance from the thyroid gland so that 
it is now prepared pure for the physician. It is not too much 
to hope that similar substances will be isolated from other 
