474 MUSGRAVE, CLEGG, AND POLK. 



crystals and unstainable detritus. The arrangement of the peripheral 

 filaments may or may not be radial and there are various degrees of 

 density of the mass. In two of our cultures (S. canis and 8. caprae) 

 there is less tendency to suppuration after inoculation in animals and 

 the individual colonies have more the appearance of tubercles than in 

 our other cultures. This difference has been pointed out by other 

 observers. However, the lesions in our experimental animals were small ; 

 in the older lesions the type of the granule is not known, if we except 

 the knowledge gained from the statements of the authors who described 

 the parasites, the description being taken from the original lesions. The 

 granules or colonies yjroduced by the other cultures were in the majority 

 of cases free in the necrosed, liguefied substance found in the various 

 channels produced by these infections. 



Club formation, in the lesions, in tissues and less frequently in cultures, 

 is used as one of the points of differentiation between species of the 

 organisms of this group. No doubt there is considerable variation in 

 this respect under certain conditions, but the circumstances reported as 

 surrounding club development are sufficiently varied and confusing to 

 detract somewhat from what would otherwise be valuable for purposes 

 of distinction. 



Wright found club formation to be rather constant in original lesions, 

 and observed it occasionally in certain cultures. In experimental lesions, 

 it was also fairly constant, except in early lesions where clubs were some- 

 times absent. 



Bostroem and others, working with species differing somewhat from 

 Wright's organism in other particulars, also observed clubs both in lesions 

 in animals and occasionally in cultures. 



None of our cidtures show definite clubs in culture or in experimental 

 lesions in animals, although in several the terminal branches show some 

 enlargement suggesting club formation (see illustrations). Our experi- 

 mental animals were all killed within a shorter time after inoculation 

 than were those of Wright, in which clubs were found. 



Branching is similar in all of our cultures and is also similar to that 

 recorded by most observers who have worked with this group of micro- 

 organisms. 



The cultural characteristics of all of our strains have already been 

 described. ' While there are variations in the reactions between some of 

 these strains, they all appear to belong to one group of organisms, and if 

 we analyze the literature carefully others, including the organisms of 

 Wright and of Bostroem, may also be included in the group. 



The following may be noticed if we take up the principal cultural 

 characteristics comparatively as well as somewhat more in detail. 



Surface growth is considered to be poor in Wright's organism and is not very 

 profuse in some of our strains, but in Bostroem's organism and in most of ours, 

 while it may be slow, it does occur in a satisfactory manner and in some strains 



