204 SPECIAL BACTERIOLOGY 



brownish pigment. The action is the same when the lymph is injected 

 into the vein on one side of the neck, and the immune blood into the 

 vein on the opposite side shortly afterwards. In different outbreaks of 

 the disease the virulence of the lymph is extremely variable, therefore 

 experiments are necessary to obtain, if possible, a lymph of constant 

 action. Further experiments were also conducted with lymph reduced 

 with thirty-nine parts of water and mixed with a considerable quantity 

 of a culture of the Bacillus fluorescens (as a test if any germs passed 

 through the filter), and the whole mixture filtered two or three times 

 through a porcelain filter. Cultivations instituted on various media with 

 the filtrate remained sterile, thus proving that no bacterial elements had 

 passed through the filter. A number of calves were injected intra- 

 venously with this filtrate, and at the same time others with lymph. 

 The animals inoculated with the filtrate were affected at the same time 

 as those inoculated with the lymph, presenting all the typical symptoms 

 of the disease, high fever, vesicles in the mouth and feet. 



The Commission explain these results by two possibilities. The 

 bateria-free filtered lymph either contains an extraordinary strong 

 working soluble poison, or the not yet discovered causes of the disease 

 were so small that they were able to pass through the pores of the 

 filter, which safely prevents the smallest known bacteria passing through. 



In conclusion, the Commission adopt the hypothesis that foot and 

 mouth disease is caused by an organism that is so small that it is able to 

 pass through the porcelain filter. The smallest of all known bacilli is 

 Pfeiffer's bacillus of influenza, which is 0*5 to 1 /* long ; and if the 

 supposed cause of foot and mouth disease was only T 1 5 or i the size of 

 those, which is not impossible, they would, according to Professor Abbe 

 of Jena, be beyond the limit of the working capabilities of our 

 microscopes, and could not be recognised with the best oil immersion 

 systems. The results obtained by M. Nocard and his colleagues in their 

 researches with pleuro-pneumonia contagiosa (see page 202) tend to 

 strengthen the hypothesis advanced by the Commission. The Com- 

 mission also consider that other infectious diseases of man and animals, 

 i.e. smallpox, cowpox, scarlet fever, measles, spotted typhus, rinderpest, 

 the causes of which are as yet unknown, may possibly belong to this 

 group of extremely small organisms. They also consider that the 

 preparation of a bacteria-free cowpox lymph would remove the agitation 

 against vaccination. 



CANINE DISTEMPER. 



According to the recent researches of Schantyr, three diseases are 

 included under the name ' Distemper,' which can only be differentiated 

 from each other by bacteriological examination. 



