2i2 THE POPULAR SCIENCE MONTHLY 



his studies in isolysins which inaugurate a physiology peculiar to the 

 individual as opposed to the normal physiology of the species ; his idea 

 of a canonical study of the blood-serum in health and disease, so that a 

 norm or " blood-canon " for the investigation of new or unknown con- 

 ditions may be available ; his demonstration that cancer may be changed 

 into sarcoma by successive inoculations ; that the growth of cancer in an 

 animal body depends upon the presence of certain food-stuffs in that 

 body; finally the gigantic labors involved in building up hundreds of 

 new compounds and testing them as remedies for the two great groups 

 of parasitic diseases, the spirilloses and the trypanosomioses, his pros- 

 pective success being one of the greatest triumphs of the method of 

 " trial and error " on record. Surely a career in scientific medicine 

 only matched in recent times by those of Pasteur, Helmholtz, Koch and 

 Lister. 



To the orthodox chemist, who works by rule and formula, Ehrlich's 

 experimental methods might seem mere haphazard " test-tubing," and 

 he himself has jestingly referred to his laboratory procedure as " Spiel- 

 chemie," an epithet which well describes the experimentation that re- 

 sults from the free play of a singularly acute mind. Some of his 

 admirers have even gone so far as to say that he declines to work quanti- 

 tatively. Although his own statement (in the Harben lectures) is just 

 to the opposite effect — and all experiment that seeks the general law 

 behind related facts is obviously quantitative in its intention — it is 

 quite true that Ehrlich has steadfastly declined to follow Arrhenius in 

 applying the quantitative methods of physical chemistry to the unknown 

 entities of immunity reactions. " I have always emphasized the chem- 

 ical nature of the reaction," he says, only " the formulas devised by 

 Arrhenius and Madsen for the reactions of toxins and antitoxins ex- 

 plain absolutely nothing. Even in particularly favorable cases they can 

 merely represent experimental results in the form of interpolation 

 formulas."* In Ehrlich's view, the mistake made by the distinguished 

 Swedish physicist lies in the assumption that toxins and antitoxins can 

 be treated mathematically as simple indivisible substances, whereas 

 there is unimpeachable evidence of their dual and multiple nature — 

 that they can be split up into labile components of such extreme com- 

 plexity as to have, so far, defied ultimate analysis. Under these con- 

 ditions assumed constants become inevitably dependent variables and 

 the physical chemist is dealing with the shifting evanescent aspects of 

 substance in the labile state. The careful quantitative work of such a 

 competent experimenter as Dr. W. H. Manwaring 5 has shown that, 

 with the knowledge at present available, physico-chemical measure- 



1 Ehrlich, " Collected Studies in Immunity," New York, 1906, 578. 



"Manwaring, Jour. Infect. Dis., Chicago, 1907, IV., 219-222; Jour. Biol. 

 Chem., New York, 1907-8, III., 387-389; Brit. Med. Jour., London, 1906, II., 

 1542-1547. 



