1893.] Bacteriology in its General Relations. 1057 
nutrition or not, it is difficult, if not impossible to say. The 
question may fairly arise, whether they are due to variations 
in the food medium or are they entitled to the dignity of 
varieties and species in the taxonomie sense. 
Reproduction is considered one of the most complex 
and deep seated phenomena of organic life. If we are able 
experimentally to change the inner constitution of an organic 
structure to such an extent as to permanently modify its 
reproductive function, we may justly conclude that a profound 
change in the original type has been induced. This has been 
done in the case of the anthrax fever germ. The bacillus that 
causes this malady is characterized by the ease with which 
endospores are produced. With a favorable temperature and 
free oxygen, spores are formed in the vegetating filaments in 
the course of from 24 to 36 hours. Roux succeeded in produc- 
ing an asporogenous race of this bacillus by growing them in 
a nutrient culture medium to which potassium bichromate had 
been added in the proportion of 1 to 2000. He also led in 
modifying this reproductive function by the use of phenol. 
Cultures containing 6 parts of phenol in 10,000 produced endo- 
spores in a normal manner, while those seeded in 20 parts to 
10,000 were destroyed. Between these limits, the cultures 
maintained their vitality and grew, but in no case formed 
spores. When these asporogenous cultures were re-seeded into 
normal media, they vegetated in a normal manner but did 
not form spores, although the conditions were most favorable 
for the process. Behring succeeded in obtaining the same . 
results by the use of rosolic acid. What these observers. 
accomplished by the strict control of cultural conditions, Leh-. 
mann observed under more natural conditions. He found 
` that certain cultures that had been cultivated in Koch's 
laboratory for many generations on gelatine exclusively had 
lost their ability to produce spores, but their virulence had 
not been impaired in the least degree. They could not be 
distinguished from the normal spore-bearing forms in any 
other than this particular. He tried to modify these varieties, 
and when the asporogenous type had been grown on a medium 
suitable for spore production, like potato, for a series of gener- 
71. 
