THE MULTIPLICATION OF MICRO-ORGANISMS 249 



of this precaution on the part of the former, and men- 

 tions that in one experiment in which he used tubercle 

 bacilli, in spite of every effort being made to obtain 

 the latter in an isolated condition, on an examination 

 of the water after agitation in the centrifugal machine, 

 and without additional shaking, very few and only 

 isolated bacilli were found in the upper and middle 

 layers of the water, whilst at the bottom of the vessel 

 numerous conglomerates of bacilli often consisting of 

 more than 100 individuals were noticed. The precise 

 figures given are : 50 tubercle bacilli per c.c. in the 

 original suspension, 10-15 in the upper layers, 20-25 

 in the middle and 1,000 and more at the bottom, after 

 10 minutes' centrifugal action. 



Experiments were also made with other organisms, 

 and in all cases Scheurlen found after agitation in the 

 machine that more organisms were present in the bot- 

 tom than in the upper layers of water. 



This explanation of Poehl's results does not, how- 

 ever, appear to us as adequate, inasmuch as Poehl 

 professes to have obtained similar reductions in the 

 numbers of bacteria when the bottles were shaken 

 with the hand, and not with the centrifugal machine 

 at all. 



The above represent only a few out of a large 

 number of experiments which bear directly or in- 

 directly on this important and interesting question, as 

 to whether mechanical motion is favourable, unfavour- 

 able, or without effect on the multiplication of bacteria. 

 In order, however, to indicate the contradictory results 

 which have been obtained we cannot do better than 

 quote the following passage from a paper by Wolffhligel 

 and Hiedel(Arbeiten a. d. kaiserlichen Gesundheitsamte,vol. 

 i., 1886, p. 463), in which this subject is reviewed : 



'Alexis Horvath (Pfliigers Archivf. Physiologic, 1878, 



