1919] on A Filter-passing Virus in Certain Diseases 501 



ture of 56° C. for thirty minutes ; and their thermal death-point is 

 between 65° C. and 70° C. 



We will now consider shortly the pathogenic action of these filter- 

 passing viruses. The well-defined group of glo])oids is characterised 

 by producing lesions of the nervous system of a peculiar kind, lesions 

 in which there is extensive destruction of the higher elements of the 

 nervous system, such as the nerve-cells of the brain, spinal cord and 

 ganglia. In addition, these organisms also produce lesions of the 

 blood vessels of the nervous system. The extent of these different 

 lesions varies in the different diseases, and at the present time there 

 are at least three separate diseases of the nervous system — polio- 

 myelitis, polyneuritis and encephalitis — due to the action of separate 

 and distinct organisms of this group. It is not only interesting that 

 all these nervous diseases are due to the pathogenic activities of 

 globoids, but also that in the considerable number of filter-passing 

 viruses isolated in the cause of the work at Etaples globoids have only 

 been found as yet in these nervous diseases. Rabies, however, is a 

 disease of the nervous system with not distant analogies to these 

 other nervous diseases, but the organism isolated in rabies is not a 

 globoid so far as we can say at present. 



The other filter-passing viruses isolated and experimented on at 

 Etaples produce well-marked and characteristic diseases, e.g. influenza, 

 trench fever and nephritis. Trench fever is relatively to the others 

 a mild disease, and we know nothing of the morbid anatomy and 

 lesions of this disease, as such a thing as death from trench fever is 

 unknown. In influenza the virus produces widespread lesions in the 

 lungs and other organs of experimental animals, similar to those 

 seen in man. Similarly in nephritis it is possible to reproduce the 

 disease in the laboratory and so to study it in a way that was pre- 

 viously impossible. It will suffice to say here that all these viruses 

 have to some degree a similar action; thus they all produce lesions 

 of the smaller blood vessels, and many of them produce nephritis 

 to some degree, but their action is also specific. Thus the virus of 

 influenza produces its main effects on the lungs, heart and liver, and 

 but little on the kidney ; whereas the virus of nephritis produces but 

 little effect on the lungs, none on the liver, and its main action is 

 spent on the kidney. It was extremely fortunate that these researches 

 were carried on concurrently, since in this way the results obtained 

 with one virus served as a kind of control on those obtained with 

 another virus grown under the same conditions but obtained from 

 a different malady. In this way it was possible to obtain results 

 rapidly as to the specific nature of the separate viruses. 



The work done at Etaples dealt more especially with these six 

 maladies — and in regard to them Koch's postulates were fulfilled — 

 but in addition a series of observations was made on the possibility 

 of detecting filter-passing organisms in other diseases, and more 

 especially in the acute specific fevers. This group of diseases is one 



