658 SUMMARY OF CURRENT RESEARCHES RELATING TO 



where they have the form of cloudy masses at the bottom of the 

 perfectly clear nutrient fluid. If the temperature is raised to 36°, 

 and the supply of oxygen increased by shaking, they multiply 

 more rapidly, and at the same time gradually lose their infectious 

 properties. 



In order to convert the distemper-bacteria rapidly into hay- 

 bacteria, the solution which contains them is shaken up violently, to 

 increase the supply of air, in a vessel to the sides of which pieces of 

 filtering paper are stuck. Three transitional forms are thus obtained, 

 which finally pass over into the bacteria of hay. The change is 

 greatly promoted by the addition to the solution of extract of meat, 

 of yolk of egg, and a small quantity of alkali. After standing for 

 about 24 hours at a temperature of 36° C, a transitional form, the 

 bacteria of white of egg, is obtained, which, in a slightly acid infusion 

 of hay, is transformed into the innocuous hay-bacteria. 



The following is an epitome of the behaviour of these three inter- 

 changeable forms of bacteria, which Buchner regards as adaptive 

 forms of one and the same organism, Bacterium subtile : — 1st medium. 

 1 per cent, extract of meat — (a) distemper-bacteria : solution clear, 

 clouds at the bottom; (b) white-of-egg-bacteria : solution cloudy, floccu- 

 lent, a mucilaginous pellicle, flocks and pieces of pellicle at the bottom ; 

 (c) hay-bacteria : solution clear, with a firm, white, dry pellicle diffi- 

 cult to submerge. 2nd medium. Slightly acid infusion of hay. 

 (a) no increase ; (b) formation of a sparse white rim on the surface of 

 the fluid ; (c) dry pellicle, moistened with difficulty, and usually with 

 a wrinkled or pulverulent appearance. 3rd medium. The bodies of 

 animals, (a) Infectious in very small quantities, producing dis- 

 temper ; (b) when multiplied a thousandfold, inactive ; in still greater 

 quantities, infectious, producing distemper; (c) inactive even when 

 present in the greatest quantities. 



Diffusion of Bacteria. — The researches of Pasteur and Darwin 

 have shown how earthworms may aid the diffusion of small organisms, 

 some of which may produce disease. Professor J. B. Schnetzler states 

 that the dejections of earthworms always contain numerous living 

 bacteria and their germs (the hay-bacterium included). It is clear that 

 bacteria in enormous quantity float in the air about us ; and we have 

 at easy command, Professor Schnetzler points out, a small apparatus 

 traversed by about 8000 cubic centimetres of air per minute, which 

 may inform us as to those floating germs. This is no other than the 

 nasal cavity, on the mucous surface of which air-particles are de- 

 posited. To observe these he advises injecting the nose with distilled 

 water (completely sterilized) by means of a glass syringe previously 

 calcined. The liquid so obtained is put in one perfectly clean watch- 

 glass and covered by another. With a Microscope magnifying 700 or 

 800 one finds, among various particles in the liquid, some real live 

 bacteria. If the liquid be kept a few days in a clean glass tube 

 hermetically sealed the bacteria are found to have increased very 

 considerably. One sees Bacterium termo, Vibrio, Spirillum, Bacillus 

 subtilis, even some Infusoria, and spores and fragments of fungi. 



