BACTERIA IN WATER. 637 
present in a living condition on the second day, but no colonies de- 
veloped after the third day ; the typhoid bacillus died out between 
the fifth and seventh days ; the cholera spirillum was no longer found 
on the second day. In the meantime the common water bacteria 
had increased in numbers enormously. Similar results have been 
reported by Hochstetter and others. Hueppe, in ten experiments in 
which the typhoid bacillus was added to well water of a bad quality, 
found that in two no development of this bacillus occurred after the 
fifth day, while a few colonies developed in the other experiments as 
late as the tenth day. In these experiments the temperature was 
comparatively low (10.5° C.). At a higher temperature the experi- 
ments of Wolffhiigel and Riedel show that an increase may take 
place. At the room temperature (about 20° C.) the typhoid bacillus 
added to distilled water, to well water, and to Berlin hydrant water 
was still present, in some instances, at the end of thirty-two days. 
And it was found that in some cases a decrease in the number 
occurred, then a notable increase, and finally a second diminution. 
Koch found the cholera spirillum in a water tank at Calcutta 
during a period of fourteen days, and in his experiments showed that 
it preserved its vitality in well water for thirty days, in Berlin sewer 
water for six to seven days, and in the same mixed with feces for 
twenty-seven hours only. In the experiments of Nicati and Rietsch 
the cholera spirillum preserved its vitality in distilled water for 
twenty days, in sewer water (of Marseilles) thirty-eight days, in 
water of the harbor for eighty-one days. The numerous experiments 
recorded by the observers named, and by Bolton, Hueppe, Hoch- 
stetter, Maschek, Kraus, and others, show that while the cholera 
spirillum may sometimes quickly die out in distilled water, in other 
experiments it preserves its vitality for several weeks (Maschek), and 
that it lives still longer in water of bad quality, such as is found in 
sewers, harbors, etc. Bolton found that for its multiplication a 
water should contain at least 40 parts in 100,000 of organic material, 
while the typhoid bacillus grew when the proportion was considerably 
less than this—6.7 parts in 100,000. 
Russell (1891) has studied the bacterial flora of the Gulf of 
Naples, and of the mud at the bottom of this gulf, collected at 
various depths up to eleven hundred metres. His investigations 
show that sea water does not contain as many bacteria as an 
equal volume of fresh water; that bacteria are found in about 
equal numbers in water from the surface and in that from various 
depths ; that the mud at the bottom constantly contains large num- 
bers of bacteria; that some of the species isolated grow best in a 
culture medium containing sea water. 
At a depth of 50 metres the water contained 121 bacteria per cubic 
