ON AtMOSPHERIC BACTERIA. 88 



with two large water jars by a caoutchouc tube. The wash bottles 

 were then connected by tubing which was previously subjected to 

 prolonged boiling, as were the stoppers ; the glass tubing and the 

 cotton wool was heated in an oven to over 100° C. for a considerable 

 time. The aspirator formed by the water jars was then set in 

 motion, and upwards of 100 Lts. of air drawn through the wash 

 bottles, at the rate of about 2 Lts. an hour. The aspirator being 

 only worked mornings and evenings, this occupied between two and 

 three days. The experiments were made in an ordinary sitting- 

 room, the temperature of which varied between about 50° F. and 

 70° F. An uncovered bottle of the solution was placed near 

 the wash bottles for comparison. When the requisite quantity 

 of air had passed through, the bottles were removed, the entrance 

 tube of the first wash bottle was rinsed out into a fresh bottle of 

 the solution by a stream of water from an ordinary wash bottle, 

 previously boiled, and cooled with precautions against contami- 

 nation ; the cotton wool at the bottom of the exit tube of the 

 last wash bottle was pushed into the fluid of its own bottle by a 

 thin rod previously heated. All the bottles were then covered 

 with watch-glasses, and placed in the incubator at 35° C. The 

 result was that in twenty-four hours the fluid in the uncovered 

 bottle was found to be shghtly turbid, containing bacterioid 

 growth, the same with the bottle into which the entrance tube 

 of the first wash bottle had been rinsed, while that of the last bottle, 

 into which the cotton wool had been dropped, was distinctly 

 more turbid ; but the solution in the first wash bottle remained 

 free from Bacteria, and continued so for several days, as long as 

 observed. A microscopical examination showed that the num- 

 bers of Bacteria present in the diff'erent bottles corresponded to 

 the macroscopical appearances mentioned above. 



From these observations it is concluded, that when atmospheric 

 air is drawn through wash bottles containing cultivation fluids, 

 part of the Bacteria present are entangled in the tube by which 

 the air enters, as might have been anticipated from the well- 

 known experiments of M. Pastern and others ; and that part of 

 them are " washed out'^ by the current of air, as conjectured by 

 Cohn ;i which latter, in these experiments, were caught by the 

 plug of cotton wool. 



The above observations refer only to Bacteria ; no mention is 

 made of other organisms or bodies, of which, and of the different 

 species of Bacteria present, with their relative numbers, an account 

 will be given in a subsequent communication ; and further details 

 of the experiments, with the results of observations on other 

 points which have suggested themselves. 



1 'Beit. z. Biol. d. Pflanien,' 3 H., 146 S., 1875. 



