176 



SCIENCE 



[N. S. Vol. XLII. No. 1075 



in the discovery by Claude Bernard of gly- 

 cogen in the liver! Innumerable fruitful 

 researches have come from this as a start- 

 ing-point, and their bearing on our under- 

 standing of such diseases as diabetes mel- 

 litus has been of the most fundamental na- 

 ture. 



Miescher's discovery of the existence of 

 protamin nucleate in the spermatozoan 

 heads of the Rhine salmon is another case 

 of the far-reaching importance of a definite 

 chemical fact for both biology and medi- 

 cine. For further discoveries in the field 

 of nueleinie acids, a later worker, Professor 

 Kossel, received the Nobel prize. To name 

 only one practical outcome of these discov- 

 eries, our theories of the origin of uric acid 

 in gout and of the purins in general have 

 undergone entire transformation. 



The actual finding of definite and spe- 

 cific chemical principles in the organs of 

 internal secretion has in each case an im- 

 portance in the way of explaining and cor- 

 relating a large number of disconnected 

 facts, only to be likened to the discovery of 

 the etiological cause of an infectious dis- 

 ease. The bacilli of tuberculosis or of 

 typhoid, or the protozoa of syphilis and 

 sleeping-sickness, are illuminating ex- 

 amples in point. Here, too, simplicity at 

 once took the place of what had been con- 

 fused and complex, and a multitude of al- 

 ready recorded facts fell into their proper 

 place. 



Prom my insistence on our ignorance of 

 the specific secretory products of the or- 

 gans of internal secretion, and of numerous 

 constituents of the blood, it is not to be in- 

 ferred that important chemical facts are 

 lacking with regard to these tissues. On 

 the contrary, a vast number of facts, some 

 of immediate, others of potential signifi- 

 cance, have been amassed by an army of 

 workers in the past 30 years; it is their 

 relation to each other and to an xmderlying 



cause which remains obscure. For ex- 

 ample: it has been recently shown by 

 Cramer and Krause*^ that when fresh thy- 

 roids are fed to cats or rats kept on a car- 

 bohydrate-rich diet, the glycogenic func- 

 tion of the liver is inhibited, and in 

 consequence this organ is soon found to 

 contain only traces of glycogen. And 

 these investigators suspect that the well- 

 known action of thyroid secretion on the 

 metabolism is effected through this change 

 in the carbohydrate metabolism. But this 

 important discovery can not reach its full 

 significance until we know the chemical 

 properties of the special hormone of the 

 thyroid gland which is carried in the blood 

 to the liver and there prevents the forma- 

 tion of glycogen even though the food may 

 contain an abundance of carbohydrate. 



Thus, too, one of the facts known about 

 the parathyroids, as shown by MacCallum 

 and Voegtlin,*^ is that their removal from 

 the body is followed by increased excretion 

 of calcium salts. This chemical discovery 

 also can not yet be brought into a causal 

 connection with a definite chemical constit- 

 uent of the gland. 



That I may not be accused of placing too 

 much emphasis upon only one mode of 

 attack in biological and medical research, 

 let me say that I am fully aware of how 

 many-sided are all these problems, and that 

 fundamental discoveries have been made 

 and will continue to be made without the 

 aid of chemistry. This is true especially in 

 the field of morphology. But as soon as we 

 touch the complex processes that go on in 

 a living thing, be it plant or animal, we are 

 at once forced to use the methods of this 

 science. No longer will the microscope, the 

 kymograph, the scalpel avail for the com- 

 plete solution of the problem. For the 

 further analysis of these phenomena which 



i-^Froc. Soy. Soc. B., Vol. 86, p. 550, 1913. 

 ^Jour. Exp. Med., Vol. 11, p. 118, 1909. 



