November 22, 1912] 



SCIENCE 



697 



upon the blood of inoculated monkeys. 

 The virus remained alive within these in- 

 sects for a period of many days. The 

 inoculation of monkeys with a filtrate pre- 

 pared from them gave rise to characteristic 

 paralysis and anatomical lesions. This re- 

 sult is significant, since it shows that insects 

 are capable of taking up the virus from 

 the blood where it exists in minimal quan- 

 tities and in harboring it for a considerable 

 period in an active state; but it does not 

 show that multiplication occurs within 

 them or that in, nature they act as the 

 agents of inoculation. A tentative an- 

 nouncement has been made recently by 

 Kosenau^* that the stable fly {Stomoxys 

 calcitrans) can take up the virus from the 

 blood of infected monkeys and reinoculate 

 it into healthy ones which will become 

 paralyzed. The experiment awaits con- 

 firmation and, after confirmation, convin- 

 cing application to the circumstances sur- 

 rounding infection in human cases of 

 poliomyelitis. 



The frequent prevalence of epidemics in 

 sparsely populated country districts has 

 led, moreover, to consideration of domestic 

 animals as sources of the infection. Paral- 

 ysis of dogs, horses, pigs and fowl has been 

 observed, not uncommonly, but thus far 

 without clear correlation with paralysis in 

 man. Perhaps the most frequently ob- 

 served coincidental paralytic diseases have 

 been between hens and human beings. 

 Undoubtedly since the wide prevalence of 

 epidemic poliomyelitis, the existence of a 

 paralytic disease among barnyard fowl has 

 been more commonly noted. Possibly the 

 condition has not actually become more 

 frequent, but owing to the circumstance 

 mentioned it has been oftener observed. 

 It appears that the paralysis among fowl 



" Eosenau, eommunieation at the International 

 Congress of Hygiene and Demography, Washing- 

 ton, 1912. 



is caused not by lesions of the central 

 nervous system, but by lesions of the 

 peripheral nerves and is due to a periph- 

 eral neuritis. It has not been found pos- 

 sible to transmit by direct inoculation the 

 paralytic disease from chicken to chicken, 

 or from chicken to monkey, or from para- 

 lytic monkey to chicken. However, it has 

 been found possible to develop the paralysis 

 in the laboratory by keeping the chickens 

 in confinement for some time, and by sup- 

 plying them an unusual and improper 

 form of food. It has proved as little pos- 

 sible to transfer the paralytic affection of 

 dogs from one individual to another by 

 direct inoculation, or from dog to monkey, 

 or from paralyzed monkey to dog, or to set 

 up paralysis in monkeys by inoculating 

 them with nervous tissue obtained from 

 paralyzed pigs, or to produce paralysis in 

 pigs with the virus of paralyzed monkeys. 

 These failures do not, of course, exclude 

 the possibility that a reservoir for the virus 

 may exist among domesticated animals that 

 do not even respond to its presence by 

 developing paralysis or other conditions 

 which could be recognized as resembling 

 poliomyelitis in man. The manner of ac- 

 tion of the virus of poliomyelitis in rabbits 

 provides an illustration which shows how 

 necessary it is to avoid general deductions 

 in this field. At first it was strenuously 

 denied that rabbits could be infected at all 

 with the virus of poliomyelitis, and the 

 examples of supposed successful inocula- 

 tion reported were entirely disbelieved; 

 but it must now be accepted that young 

 rabbits occasionally, but by no means gen- 

 erally, are subject to inoculation with the 

 virus of poliomyelitis, at least after it has 

 passed through a long series of monkeys. 

 Apparently a small percentage only of the 

 inoculated rabbits develop any obvious 

 symptoms, and these die, as a rule, during 



