J-uXY 1, 1904.] 



SCIENCE. 



11 



medicine a situation analogous to that 

 created in cliemistry by Pasteur and van't 

 Hoff and developed largely by the latter 

 and Fischer. In this new medical chem- 

 istry there is the same distrust to overcome 

 which was encountered by van't Hoff in 

 the first years after the publication of his 

 work on chemistry in space. It may be 

 recalled that Kolbe especially was very 

 bitter against what he called idle specula- 

 tion and this is the attitude to-day toward 

 an attempt to explain obscure phenomena 

 in etiology in chemical language. It is 

 true that complete chemical explanations 

 of pathological conditions are in most cases 

 not yet possible, but the bold speculations 

 of Ehrlich, Buchner, Bordet and the other 

 scientists who have contributed to the dis- 

 cussion deserve cordial recognition. It is 

 no fatal objection to their hypotheses that 

 the leaders in the various schools differ as 

 to details. The fact of permanent value 

 is that they are all at work on a theory 

 which is essentially chemical. 



The organic chemistry of the protein 

 substances has advanced far enough to 

 show that these bodies are complex aggre- 

 gations of certain large and small groups. 

 The elimination or destruction of some of 

 these groups may not necessarily mean de- 

 struction of the whole molecule. Doubtless 

 it may remain a protein with several of the 

 smaller groups lost. Outside of the ani- 

 mal or vegetable organism there is appar- 

 ently no simple way of regenerating what 

 has been obliterated. In the living tissues, 

 however, the proteins may possess the 

 power of self -regeneration by some kind of 

 a synthesis ; the loss of a few amino groups, 

 for example, need not be followed by the 

 decay of the whole. These amino groups 

 may be convenient points of attack for cer- 

 tain reagents, but not for others. They 

 are, in a sense, the toxophil groups by 

 means of which outside connection is made, 

 but if the proper attacking agent is not 



used the protein remains unchanged. It 

 is also true that certain reagents may in- 

 crease the stability of the protein and in- 

 hibit practically its destruction under 

 given conditions. In general such mole- 

 cules possess greater stability in presence of 

 their dissociation or reaction products. 

 Conceptions somewhat analogous to these 

 are included in the Ehrlich immunity 

 theory, according to which some of the 

 separated side chains from the over-stimu- 

 lated cell behave as antitoxins to cheek 

 further action. 



In still another important direction the 

 influence of chemistry is being felt in 

 medicine and it is the new physical chem- 

 istry which is now the vitalizing force. In 

 one of his earlier papers van't Hoff called 

 attention to what this kind of chemistry 

 might do for physiology, and in recent ad- 

 dresses he has come back again to the sub- 

 ject. Ostwald has many times, and even 

 more strongly, pointed out the importance 

 of physical chemistry to the progress of 

 medical theory. As long as physiology 

 alone was concerned in this advance the 

 influence on practical medicine remained 

 somewhat problematical. The clinician 

 has been almost as skeptical about the value 

 of pure physiology as he has been about 

 the value of pure chemistry. But many of 

 the newer developments from the theory 

 of solutions have been found applicable in 

 questions of pathology, the recognition of 

 which fact is of growing importance. A 

 few of these so-called practical applications 

 may be mentioned here. 



It is a well known yet always interesting 

 fact that the osmotic pressure of the blood 

 remains within narrow limits a constant. 

 A slight increase following meals or a de- 

 crease following large consumption of water 

 is speedily corrected through the activity of 

 the kidneys. The importance of this con- 

 stancy in osmotic pressure appears when it 

 is recalled that all the other organs of the 



