DEVELOPMENT OF THE BACTERIA. 107 



these of so small a diameter that they pass through 

 all filters. 1 Cohn has proved that some are not 

 arrested by a super position of sixteen filters. The 

 only waters which do not contain them are those 

 drawn from the very source of a spring. 



DISSEMINATION OF BACTERIA IN THE HUMAN 

 ORGANISM. 



If bacteria are so generally disseminated in the 

 great external media, it is not surprising that they 

 are found on the surface of the human body and 

 in the interior of the organs in communication 

 with the exterior. But to account for their pres- 

 ence in the interior of organs we find ourselves in 

 presence of two hypotheses: one admitting the 

 spontaneous production of these organisms in the 

 interior of the tissues, the second explaining it 

 by the introduction through the membranes of the 

 germs of bacteria from without. 



1 Having been directed by the National Board of Health to make 

 some experiments with a view to confirming or disproving the results of 

 Klebs and Crudelli, who claim to have found the germ of malarial fevers 

 in the atmosphere of the Pontine marshes near Rome (their Bacillus ma- 

 laria), I aspirated ten gallons of air on the edge of a swamp in the vicin- 

 ity of New Orleans, through 4 c.c. of distilled water. Upon examining 

 this water with the microscope on the following morning, I was surprised 

 to find a large number of actively moving bacteria and monads (Monas 

 lens). To make sure that these really came from the air, I examined my 

 distilled water, which had been standing in the laboratory for several 

 weeks (in a bottle, corked, but occasionally opened as distilled water was 

 required) and found the s-ame forms present in considerable numbers, 

 not so numerous, however, as in the water through which swamp air had 

 been drawn. As the germs were present in the distilled water, I presume 

 that the passing of air through it for several hours, and the organic 

 matter contained in it, favored the development and multiplication of 

 these micro-organisms. Subsequent experiments with freshly distilled 

 water gave very different results as to the number of organisms found 

 G. M. S. 



