688 



SCIENCE 



[N. S. Vol. XXXVI. No. 934 



views have all alike been treated with more 

 or less scepticism by the medical profes- 

 sion ; in how far they have come to be sup- 

 ported by later acquisitions of knowledge 

 will appear. 



Apart then from these deductions, dis- 

 puted and disputable, because not sup- 

 ported by certain tests, five years ago the 

 mystery of the disease was wholly un- 

 fathomed. The outlook was suddenly 

 brightened when Landsteiner and Popper 

 in 1909^ announced the successful trans- 

 mission of poliomyelitis to monkeys, but 

 the high hopes raised were as quickly 

 dampened by the failure to propagate the 

 experimental disease beyond the first gen- 

 eration. This obstacle was immediately 

 removed when intracerebral was substi- 

 tuted for intraperitoneal inoculation, as 

 was done by Lewis and myself and by 

 Landsteiner and Levaditi." By this 

 means the disease could be and has been 

 transmitted through an indefinite number 

 of monkeys. The inoculating matter is, 

 first, the sterile spinal cord of a fatal 

 human case, and, afterwards, the spinal 

 cord of paralyzed monkeys. 



The choice of the intracerebral route as 

 superior to the intraperitoneal was not hap- 

 hazard. All the severe effects of poliomye- 

 litis are inflicted on the nervous system, 

 and upon reflection this fact at once sug- 

 gested that the parasitic cause of the dis- 



' Landsteiner and Popper, Zeitschrift fiir Im- 

 munitdtsforschung, Originale, 1909, II., 377. 



" Flexner and Lewis, Journal of the American 

 Medical Association, 1909, LIIL, 1639; Journal 

 of Experimental Medicine, 1910, XII., 227. Flex- 

 ner, Journal of the American Medical Association, 

 1910, LV., 1105. Flexner and Clark, Journal of 

 the American Medical Association, 1911, LVIL, 

 1685. Howard and Clark, Journal of Experi- 

 mental Medicine, 1912, XVI., 850. 



"For a general bibliography, see Romer, "Die 

 epidemisohe Kinderlahmung " (Heine-Medinsche 

 Krankheit), Berlin, 1911. 



ease must find favorable conditions for 

 multiplication within the nervous tissues. 

 "When the material carrying the germ is 

 put first into the peritoneal cavity it must 

 traverse the blood before it can reach the 

 nervous system, and the blood, as we know, 

 has the power to destroy many forms of 

 germ life. It could, of course, also be 

 reasoned that the specific parasite, in na- 

 ture, can not enter the nervous tissues di- 

 rectly but must us€ some external route to 

 reach them, and it must, therefore, be ca- 

 pable of surviving outside the brain and 

 spinal cord; and it could be further rea- 

 soned that an inoculation into a more ac- 

 cessible part of the body than the brain and 

 spinal cord should be effective, and if effec- 

 tive would bring stronger proof of the 

 actual existence of a parasite in the inocu- 

 lated matter. This reasoning is uncon- 

 vincing for two causes : first, the monkey is 

 not naturally subject to poliomyelitis and 

 is, therefore, presumably more difficult to 

 infect at all than is man so that what may 

 suffice to cause infection in man may fail 

 in the monkey; and, second, it might be 

 possible for pathogenic microbes to reach 

 the central nervous system even in man 

 without entering the blood at all so that in 

 nature the infectious cause of poliomyelitis 

 might avoid the blood 'altogether. That 

 this possibility really exists has been proved 

 by experiment, as we shall see. Doubtless 

 the first material inoculated into the ab- 

 dominal cavity carried besides the living 

 parasites toxic or other injurious sub- 

 stances that promoted infection in the 

 monkey; but when the nervous tissues of 

 the monkey were similarly injected, being 

 less harmful, the inoculation failed. Bac- 

 teriology contains many instances of simi- 

 lar, and apparently of paradoxical nature. 

 The discrepancy has been further eluci- 

 dated, as will soon appear, but in the 

 meantime it is desirable to inquire whether 



