THE PATHOGENIC HIGHER BACTERIA 
618 
occurs. Freslily heated l^rotli, in which tlie dissolved oxygen has 
been driven off, appears to aff'ord a somewhat more hixuriant growth, 
particularly during the first few days' inoculation, but this j)recau- 
tion is by no means absolutely necessary to obtain develoi)ment. 
Prolongefl culti^'ation in broth frequently causes the organisms to 
lose the discrete, mulberry-like colony; the growth becomes some- 
what flocculent and viscid. Milk and other artificial media, aside 
from agar and bouillon, are not fa^•orable for the development of the 
organisms. 
Actinomyces bovis does not grow at temperatures much below 37° 
C Development ceases at room temperature. The resistance to 
drying is considerable, fifty days being about the minimal time required 
to prevent growth. In artificial media, liowever, the organism usually 
becomes non-^'iable in a shorter period. The thermal death-point is 
about ()2° C. for five minutes. Toward ordinary antiseptics, Actino- 
- Actinomyces — mycelioid development, semi-diagrammatic. 
myces is very resistant, but it is claimed that methylene blue is strongly 
germicidal to it. 
Products of Growth.— Neither toxins nor enzymes have been detected 
in cultures of Actinomyces bovis. It is believed that toxins are not 
produced. 
Pathogenesis. — .l?ii7/?o/ ajicl //wwa??.- Actinomycosis occurs as a 
spontaneous infection both in cattle and in man; much more commonly, 
however, in the former. Other mammals— horses, asses and sheep— 
are occasionally infected. The lesions belong to the group of the 
infectious granulomata and the portal of entry of the organism is 
usually the mouth, although cutaneous infections have been described. 
The mouth and adnexa and the pharynx are more commonly the site 
of the initial localization of the organism, but the lungs or the alimen- 
tary canal may be first involved. Actinomyces-like granules, com- 
posed of fusiform bacilli, streptococci and spirochetes, which are more 
or less commonly found in the crypts of the tonsils must not be con- 
