36 Veterinary Medicine. 



This gives the cluster the appearance of a daisy or other composite 

 flower, though as Bostrbm has shown, the arrangement is that of 

 a hollow hemisphere, the filaments being attached to the ends of the 

 club-shaped cells on the concave side of the sphere. Occasionally 

 a filament is to be seen with only two or three terminal club- 

 shaped cells, and again a filament will grow out of the convex 

 aspect of the hemispherical mass and develop a cluster of the 

 characteristic cells beyond. In the older actinomyces clusters the 

 center of the hemisphere contains the finely granular degenerated 

 masses of the filaments. 



In cattle a rosette of club cells is sometimes found without dis- 

 tinct filaments and in man the new and rapidly growing colonies 

 may show the filaments mainly, with few or no clubs. 



Under a strong light or a low power of the microscope the 

 clustered ends of the clubs give the granule the appearance of a 

 raspberry. 



Under the microscope the decalcified granules are best examined 

 after staining in Gram's solution or carmine, and by a j-V oil im- 

 mersion. 



The actinomyces has been cultivated on artificial media by 

 Israel, Bostrom, Crookshank and others. The colonies, in about 

 twenty-eight days, at a temperature of 33° to 37° C, form bright 

 rosy nodules surrounded by a network of fleecy white, and con- 

 sisting of radiating filaments. In artificial cultures, clubs have 

 not been found, so that Bostrbm, Wolff and Israel look upon 

 these as involution forms. Crookshank on the other hand con- 

 siders the clubs to consist in a mucilaginous expansion of the 

 sheath due to the extra stimulus of growing in the animal tissues 

 with a rich and abundant nutrition. This pleomorphism or 

 tendency to variation according to the culture medium, has been 

 noticed by Gasperini in his extended investigation, and he found 

 that a difference in its vigor of growth on given media, and even 

 in its pathogenic properties, attached to variations in form. He 

 found moreover that the virulence was largely affected by the in- 

 tensity with which the inoculated tissue reacts and by the situa- 

 tion of the infection atrium. Among pathogenic forms Gasperini 

 claims the following as being at least temporary varieties : — 

 Actinomyces bovis (hominis), A. Canis, A. Cati, A. Bovis 

 Albi, A. Bovis Luteo, Roseus, A. Cuniculi, and A. Chro- 



