LECTURE ON BACTERIOLOGY. 
365 
The mosr, important element in the successful multiplication 
and growth of fungi seems to be the maintenance of certain 
temperatures. The temperature of the human body is necessary 
Fig. 4.— Sprio-bacteria. A, Spirochseta Obermeieri, from blood in recurrent fever 
(x 1,000); £, Spirillum undula, from bog-water, showing flagella (x 3,000). After Dallinger. 
for certain pathogenic bacteria, while ordinary temperatures 
serve for many varieties. Still there are points above or below 
which all cease to live. Immersion in boiling water rapidly 
destroys most forms, while prolonged boiling is fatal to all. It 
appears that while many forms of fully developed germs are 
easily destroyed by a temperature much less than 212° F., their 
spores are capable of withstanding high temperature with less 
risk of injury. The peculiar behavior of each species under 
observation, must, as regards the effect of heat, be carefully 
determined, ascertaining the most favorable temperature for their 
development, and the degree of heat necessary for their destruc¬ 
tion. If the conditions of temperature, media, etc., are observed 
carefully they will develop with extreme rapidity. 
In the study of the relation of a given bacterium to a cer¬ 
tain disease, it becomes necessary to attend carefully to three 
different operations. 
First , the organism supposed to cause the disease must be 
found and isolated. 
Second, it must be cultivated through several generations in 
order that absolute purity may be secured. 
Lastly , the germ must be again introduced into a healthy liv¬ 
ing being. 
If the preceding steps be successfully carried out, and the 
original disease be communicated by inoculation, and the germs 
