EHRLICH'S SPECIFIC THERAPEUTICS 213 



ment of the constantly variable constants of immunity reactions is like 

 computing the dynamics of ignes fatui. Even if the ultimate formulae 

 of toxins or protoplasm could be ascertained in the laboratory, as in the 

 case of hemoglobin or urea, it would tell chemists nothing about what 

 they are in the living body. The ultimate phenomena of life and death 

 are still (in Spinoza's classic phrase) of a kind " quce nullo numero ex- 

 plicari possunt," and Ehrlich's theory, as he predicted in his Baltimore 

 lectures, has been deeply enough rooted in experimental fact to " with- 

 stand the Northern storms." In a most interesting paper in The Pop- 

 ular Science Monthly,* Dr. A. F. A. King, of "Washington, has 

 thrown into relief the all-important point that the essential feature of 

 a living organism is the limiting, peripheral, semiporous membrane, 

 skin or sheath which, like the semipermeable membrane in physics, in- 

 vests and insulates it, preventing it from dissipating its energy, except 

 sparingly and under definite conditions. Detached from the investing 

 semipermeable membrane. Dr. King holds that cellular protoplasm is 

 " neither alive nor dead but between the two." The telling feature in 

 Ehrlich's attack upon disease is the unique way in which he has visual- 

 ized and dealt with those basic border-line substances which, in vitro, if 

 not in vivo, are "neither alive nor dead, but between the two." He 

 has clearly seen that the mathematical expressions for such labile com- 

 plexes as protoplasm or toxins do not come under Sir William Hamil- 

 ton's category of " real numbers." They may be vectorial quantities or 

 relations like those of electrical science, and might be represented 

 specially, graphically, vectorially or stereochemically to the mind's eye 

 as Ehrlich has succeeded in doing; or they might be vaguely formu- 

 lated as qualitative relations by the differential calculus. Quantities in 

 the fixed arithmetical sense they are surely not. Ehrlich's method 

 might be called a qualitative way of approaching apparently quantita- 

 tive problems of extreme complexity, a sort of rough calculus of varia- 

 tions carried out in the laboratory under conditions in which the 

 variables are well-nigh legion. His success has been due to his unrivaled 

 knowledge of the intravital and distributive relations of different drugs, 

 particularly of dye-stuffs and, on the theoretical side, to what he calls 

 his " chemicoplastic imagination." Such a feat of fantasy as his side- 

 chain theory is not only solidly built up on experimental fact, but is 

 intimately concerned with the architectonics of stereochemical formulae 

 and with certain space-intuitions which are coming to be pretty gener- 

 ally accepted by organic chemists to-day. So we find Professor H. E. 

 Armstrong, of London, stating at the Winnipeg meeting of the British 

 Association (1910)'^ that for the modem chemist "the tetrahedron is 

 the symbol of the functional activities of carbon," that " even the 

 paraffins are not to be visualized as so many ducks strung upon a ram- 



•The Populab Science Moxthlt, September, 1909, 289-296. 

 'Rep. Brit. Ass. Adv. Sc, 1909, London, 1910, 438, 446, 



