CHEMOTHERAPY IN BACTERIAL DISEASES 885 



Likewise, it is possible that a chemical may be more efficacious in vivo 

 than in vitro by reason of the formation of new and more active com- 

 pounds in vivo] or by exciting the body cells to produce antibodies for 

 the parasitic antigen or chemically facilitating such production; or by 

 the stimulation of phagocytosis, as suggested by some of our experiments 

 in the case of quinin compounds in pneumococcus infections. 1 Still, as 

 a general rule, it appears that substances without appreciable effect in 

 vitro are likely to be similarly inert in uivo. Arsenobenzol offers no 

 exception to the rule; contrary to the general impression, it possesses 

 a marked trypanocidal activity in vitro. 



It is highly probable, therefore, that experiments in vitro have a 

 definite value in chemotherapeutic research as methods of preliminary 

 orientation and in the development of monotropic chemicals. This 

 value is greater when the identical microparasite causing the definite 

 infection under study is employed in the tests. In the absence of a pure 

 culture of the particular microparasite against which a destroyer is 

 sought, or in the presence of insuperable technical difficulties, other 

 and more easily cultivated organisms closely or remotely related, or 

 even of a different biologic order, may be employed, as in the use of 

 Bacillus typhosus and other bacteria by Jacobs and his colleagues 2 

 in chemotherapeutic studies concerning anterior poliomyelitis. 



Pneumococcus Infections. As has previously been stated in Chapter 

 XXIX, progress in the chemotherapy of pneumococcus infections 

 has been made by Lamar in the treatment of pneumococcus infections 

 with mixtures of pneumococcus immune serum, sodium oleate, and boric 

 acid. Particularly valuable work in this field has been done by Morgen- 

 roth and his associates. 



Influenced less by this tradition than by the effects of the use of 

 quinin compounds as observed in experimental trypanosomiasis, and 

 by the fact that certain peculiar biologic relationships (as bile solubility) 

 have been found by Schilling 3 and Neufeld 4 to exist between trypano- 

 somes and spirilla, on the one hand, and pneumococci on the other, 

 Morgenroth and Levy 5 chose quinin and its derivatives as a basis and 

 lead for chemotherapeutic studies on experimental pneumococcus infec- 

 tions. Best results were observed with optochin (ethylhydrocuprein), 

 a synthetic derivative of hydroquinin (methylhydrocuprein), which 



1 Jour. Infect. Dis., 1917, 20, 101. 2 Jour. Exper. Med., 1916, 23, 569. 



3 Centralbl. f. BakterioL, I, O., 1902, 31, 452. 



4 Arb. a. d. k. Gendhtsamte, 1907, 25, 494; Ztschr. f. Hyg. u. Infektionskr., 1900, 

 34, 454. 



5 Berl. klin. Wchnschr., 1911, 48, 1560, 1979. 



