108 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. & 



emulsions from the cords of the dead monkeys. This is at present 

 the most accurate method of diagnosing the disease. 



Soon after these results were announced, however, Drs. J. F. Ander- 

 son and W. H. Frost of the Pubhc Health Service repeated these ex- 

 periments in the federal hygienic laboratory at Washington. They 

 obtained the disease in healthy monkeys that had been bitten by 

 Stomoxys which had previously fed on intracerebrally inoculated 

 monkeys, and further succeeded in inducing the disease in another 

 monkey by inoculation with emulsion of tjie spinal cord from one of 

 those which had been infected by the flies. 



It thus appears to have been satisfactorily demonstrated that 

 Stomoxys can transmit infantile paralysis from one monkey to another. 

 Whether this is the ordinary method of spread, remains yet to be 

 definitely shown. It has already been stated, however, how well the 

 seasonal occurrence, distribution and other facts connected with 

 Stomoxys agree with the epidemiology of the disease. 



Although many facts are well in accord with such a method of spread, 

 the results of some investigators appear at first sight to be at variance 

 with such a view, and these should be given careful consideration. 

 It has been shown by a number of workers that the virus exists in the 

 nasal mucosa. By most extensive observations, moreover, Kling, 

 Pettersson and Wernstedt in Sweden have succeeded in many instances 

 in producing poliomyelitis in monkeys by inoculating into the nervous 

 system material washed from the mucous membranes of persons who 

 had died of the disease, of those suffering from it, and of healthy 

 persons in close contact with patients. This has led them to believe 

 that the infection is ordinarily acquired through the mucous mem- 

 branes, the virus being derived from this same site in those suffering 

 from the disease. One important link is missing in this chain of evi- 

 dence, however: it has never been shown that virus derived from the 

 mucosa can produce poliomyelitis by implantation on the mucosa of 

 healthy monkeys. We must, therefore, assume a fundamental differ- 

 ence in susceptibility between man and monkey, if these results are 

 believed to have any significance in relation to the ordinary method 

 of spread of poliomyelitis. Such a difference in susceptibility is 

 improbable in view of the ease with which monkeys may be infected 

 by other methods. A second objection lies in the fact that virus direct 

 from the spinal cord can sometimes produce infection by implantation 

 on the nasal mucosa, but as the virus from the mucosa cannot, so far 

 as we know, and since, outside of the laboratory, virus from the cord 

 never reaches the mucosa of a healthy individual, the bearing of these 

 experiments on the possibility of natural transmission in this way 

 must be regarded as not yet proven. 



