322 ACTINOMYCOSIS AND ALLIED DISEASES 



shaped and spherical forms may also be seen lying free, some 

 of the latter being gonidia. 



2. Spores or Gonidia. — As occurs in other species of strepto- 

 thrix, some of the filaments of the actinomyces when growing on 

 a culture medium become segmented into rounded spores or 

 gonidia. In natural conditions outside the body these gonidia 

 become free, and act as new centres by growing out into fila- 



FlG. 90. — Actinomycosis of human liver, showing a colony of the 

 parasite composed of a felted mass of filaments surrounded by pus. 

 Paraffin section ; stained by Gram's method and 

 safranin. x 500. 



ments. They have somewhat higher powers of resistance than 

 the filaments, though less than the spores of most of the lower 

 bacteria. An exposure to 75° C. for half an hour is sufficient to 

 kill most streptothrices or their spores ; cultures containing 

 spores can resist a temperature from five to ten degrees higher 

 than spore-free cultures (Foulerton). Both the filaments and 

 the gonidia are readily stained by Gram's method. J. H. Wright 

 found in the case of the streptothrix isolated by him from a 

 number of cases (vide infra) that there was no distinct evidence 

 of formation of gonidia. 



