DEVELOPMENT OF THE BACTERIA. 107 
these of so small a diameter that they pass through 
all filters." 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- 
larie), 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 same 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. 
See fig. 2, plate vii.—G. M.S. 
