MICROCOCCUS LANCEOLATUS. 507 
virulence may also be effected artificially. Banti found 
that the continued passage through the bodies of guinea- 
pigs, which are not particularly susceptible, also re- 
sulted in a loss of virulence. Sanarelli states that the 
cultivation in human saliva is also attended with an 
attenuation of virulence. Cultivation in other unfavor- 
able media, or media to which substances have been 
added which restrain development, has similar attenu- 
ating effect on the virulence. 
Restoration and Increase of Virulence. The simplest 
and perhaps the most reliable method of restoring lost 
virulence for any animal is by passage through the 
bodies of highly susceptible animals of the same species. 
Occurrence in Man. The micrococcus lanceolatus is 
not infrequently present in the saliva of healthy in- 
dividuals, having been found by Sternberg in the oral 
cavity of about 20 per cent. of healthy persons exam- 
ined. It is constantly to be detected in the rusty sputum 
of patients suffering from acute fibrinous pneumonia. 
Weichselbaum reports having found it in 94 out of 129 
cases of pneumonia examined by him; Wolff found it 
in 65 cases out of 70 examined; Netter in 75 per cent. 
of his cases, and in the sputum of convalescents from 
pneumonia in 60 per cent. The more recent the infec- 
tion the greater is the number of bacteria found in the 
diseased lung areas. As the disease progresses they 
decrease in number until finally at the crisis they dis- 
appear from the tissues, though at this time and long 
after convalescence they may be present in the sputum. 
In atypical forms of pneumonia they may remain longer 
in the tissues, and in walking pneumonia they may be 
absent in the original centres of infection or present only 
as attenuated varieties, while the surrounding, newly- 
