XVlll PRESIDENTIAL ADDRESS. 



expansions of the sheath of filaments Avhich become highly 

 developed when the organism is growing in the animal tissues. 

 In some cases of Actinomycosis that I have examined lately I find 

 neither clubs nor definite mycelium, but a mass of what appears 

 to be micrococci and apparently short broken up filaments. That 

 I was dealing with Actinomycosis was subseciuently proved by 

 j)lacing a little of the growth on several tubes of agar-agar, when, 

 after several weeks' incubation at 37 degrees centigrade, I 

 obtained a series of the most luxuriant cultures of the Actinomyces 

 fungus, The naked-eye appearance of a cultivation of the 

 Actinomyces fungus is very striking and absolutely characteristic ; 

 in fact I know of no other organism that bears even the slightest 

 resemblance to it. The growth after a few days on the surface 

 of agar-agar or blood-serum at the teiiiperature of the blood forms 

 little white, shining, moist colonies, which may remain stationary 

 or increase and coalesce. In a Aveek or ten days, sometimes 

 earlier and sometimes after several weeks, the culture turns a 

 bright yellow or yellowish-brown. After a time a powdery sulphur 

 efibrescence makes its appearance on the surface of the culture, 

 which at this time begins to develop a peculiar sour smell, The 

 stage of efforescence corresponds with the breaking up of the 

 filaments into masses of cocci and chains closely resembling 

 streptococci. Preparation of the fungus, either from cultivation 

 or from the animal tissues, can be stained readily in a variety of 

 ways, Gram's and Plant's being the principal methods used ; 

 moreover, it is interesting to know that in sections of an actino- 

 mycotic growth the tissues can be contrasted Avith some differen- 

 tial .stain, which greatly facilitates the detection of the fungus 

 with the microscope. 



From this brief sketch it would appear that the detection of 

 Actinomycosis was an easy matter. So it is in the majority of 

 cases ; sometimes an accurate diagnosis by means of the micro- 

 scope, without even the aid of anilyne dye, can be made in three 

 minutes ; on the other hand, I have met cases which bafHed 

 several of us working closely together for several days, and the 

 positive result of the diagnosis was obtained solely by persistent 

 work with the microscope. Several of the cases of more than 

 passing interest are here well worthy of recording : — 



