TRICOPHYTON MENTAGROPHYTES 687 



increasing in size becomes umbilicated in the centre and is surrounded with 

 star-like rays ; at the end of a week it is covered with a white, chalky dust 

 and in a fortnight the downy appearance is again seen in the centre. 



On maltose-agar a white disc is formed downy in the centre, powdery and 

 godrooned at the margins. 



On potato ; a large white track at first downy, later chalky, is produced. 



T. mentagrophytes gives a white growth on whatever medium it is grown : 

 this fact is of importance since all species of Tricophyton which give white 

 growths are pyogenic. 



Tricophyton mentagrophytes can live as a saprophyte and grows readily on 

 garden mould, mulberry leaves, etc. 



3. Experimental inoculation. Tricophyton mentagrophytes is pathogenic 

 for man and guinea-pigs. Infection of the guinea-pig is easy ; it is only 

 necessary to pick up a little of the growth in the teeth of a pair of pressure 

 forceps and then to pinch the animal's skin between the teeth of the forceps. 

 This method of inoculation gives rise to a serpiginous tricophytosis which 

 persists indefinitely but is unaccompanied by suppurative folliculitis (Bodin). 



2. Tricophyton equinum. 



Tricophyton equinum was isolated by Matruchot and Dassonville during an epi- 

 zootic of equine herpes which was contagious for man, horses, guinea-pigs and 

 rabbits. T. equinum belongs to the endo-ectothrix sub-division. On agar it pro- 

 duces colonies which are white on the surface, but yellow or red in the depth. It 

 grows with difficulty on potato. 



3. Tricophyton caninum. 



This parasite was described by Matruchot and Dassonville as occurring in ring- 

 worm of dogs. It is an ectothrix parasite with round, ovoid or elongated spores. 

 On sugar-agar, it gives a flocculent white growth. On potato, small golden-yellow 

 colonies. This species is infective for dogs and guinea-pigs. 



4. Tricophyton felineum. 



[Syn. Tricophyton niveum Sabouraud T. radians Sabouraud. ] 

 This parasite was found in ringworm in cats, and is infective for man and most 

 of the domestic animals : in man, it produces tinea circinata dysidrosiforme (Sabou- 

 raud). It is an ectothrix parasite and pyogenic : in cultures it resembles T. menta- 

 grophytes. 



5. Tricophyton megnini. 



Tricophyton megnini is the cause of a severe tricophytosis among the Gallinaceae. 

 It may infect the human hair, in which it grows in the deeper layers in the form of 

 numerous large spores and in the superficial layers as fine mycelial filaments forming 

 a network around the hair. 



Cultures grow very slowly and have generally a ragged-white-disc appearance 

 more or less radiated. 



6. The faviform tricophyta. 



These are the parasites (described by Bodin) which produce lesions with distinct 

 ringworm characteristics, but in cultures behave like parasites of the genus Achorion ; 

 they form indeed an intermediate group between the two genera. T. faviforme of 

 the ass and of the horse are transmissible to man. 



[7. Tricophyton concentricum. 

 [Syn. Tricophyton mansoni Castellani : Endodermophyton concentricum 



Blanchard. 



[It is uncertain whether tinea imbricata (p. 700) is due to infection with a 

 species of Aspergillus or whether it is a true ringworm disease. According 

 to Manson the parasite causing the disease is a tricophyton. 



