124 THE FLOATING-MATTER OF THE AIR. 



Thus, out of 31 flasks opened in the same air, 18 

 remained intact, while 13 were taken possession of by 

 organisms — a fact obviously the same in character as 

 that described by Pasteur. Such experiments demon- 

 strate, if demonstration were needed, that it is not 

 the air itself, or any gaseous or vaporous substance 

 uniformly diffused through it, but some discontinuous 

 substance floating in it, that is the cause of the infec- 

 tion. Instead of our tubes, let us suppose thirty-one 

 wounds to be opened in the same ward of a hospital ; 

 plainly what has occurred with the tubes may occur with 

 these wounds — some may receive the germs and putrefy, 

 others may escape. Helped by the conception not only 

 of germs, but of germ-clouds, the different behaviour of 

 wounds subjected apparently to precisely the same con- 

 ditions will cease to be an inscrutable mystery to the 

 surgeon.^ 



During the course of this inquiry some eminent 

 biologists have been good enough, from time to time, 

 to look in upon my work, and to give me their views 



' ' We have ample facts of experiment in our hands,' said Mr. 

 Knowsley Thornton (Trans, of the Pathological Society, vol. xxvi. 

 p. 313), ' to show that it is not the gases of the air, or any soluble 

 material in water, but something "particulate" which sets up all 

 the train of changes in an open wound, which may, after the patient 

 has passed through a period of more or less constitutional disturb- 

 ance, end in the healing of the wound, or may end in septicaemia 

 and death. This particulate material, then, I believe we have evi- 

 dence enough to prove consists of germs of Bacteria and other low 

 organisms.' All the evidence points to this conclusion. I may say 

 that I entirely agree with Mr. Thornton in the distinction he draws 

 between germs and developed Bacteria floating in the air. It is, in 

 my opinion, of the very last importance to seize this distinction 

 with clearness. When it is fully realized we shall probably hear 

 less of the arguments against Bacterial contagia founded on the 

 fact that a virus diminishes in strength as the Bacteria multiply. 

 A portion of the energy of the virus consists in its passage from the 

 germ state to that of the finished organism. 



