326 ACTINOMYCOSIS AND ALLIED DISEASES 



internal organs. The liver is the organ most frequently affected, 

 though abscesses may occur in the lungs, brain* (where a primary 

 meningitis may also occur), kidneys, etc. In such cases the 

 spread takes place by the blood stream, and it is possible that 

 leucocytes may be the carriers of the infection, as it is not 

 uncommon to find leucocytes in the neighbourhood of a colony 



containing small portions 

 of the filaments in their 

 interior. 



Source of the Para- 

 site. — There is a certain 

 amount of evidence to 

 show that outside the 

 body the parasite grows 

 on grain, especially on 

 barley. Both in the ox 

 and in the pig the parasite 

 has been found grow- 

 ing around fragments of 

 grain, embedded in the 

 tissues. There are be- 

 sides, in the case of the 

 human subject, a certain 

 number of cases in which 

 there was a history of 

 penetration of a mucous 

 surface by a portion of 

 grain, and in a consider- 

 able proportion of cases 

 the patient has been 

 exposed to infection from 

 this source. Doubt has, 

 however, been recently 

 thrown on this view 

 (p. 328). 



Cultivation (for 

 methods of isolation see later). — The descriptions of the cultures 

 obtained by various investigators differ in essential particulars, 

 and there is no doubt that the organisms described are 

 different. We give an account of the following as the most 

 important : — 



(1) Streptothrix actinomyces (Bostrom). — On ayar or glycerin 

 agar at 37° C, growth is generally visible on the third or fourth 

 day in the' form of little transparent drops which gradually 



A B 



Pig. 93.— -Cultures of streptothrix aetino- 

 ruyces (Bostrom) on glycerin agar, of 

 about three weeks' growth. The growth 

 in A is at places somewhat corrugated on 

 the surface. Natural size. 



