270 Manual of Veterinary Microbiology. 



central zone with the fihaments of which they become 

 continuous. 



The thickness of the peripheral zone is quite uni- 

 form whatever may be the size of the actinomyces 

 itself, but it may be unequal in the different parts of 

 the same colony on account of the varying dimensions 

 of the cortical enlargements ; the average length of 

 these enlargements is from 15^a to 30/i and breadth 

 bfitol/i, but these limits may be much surpassed; 

 we have seen some which measured 74// in length by 

 10/i in thickness. 



The club-shaped enlargements may be simple or 

 branching, and branching may take place either from 

 the slender pedicle or from the enlarged part itself; 

 the branches, emerging in this manner, may them- 

 selves divide giving rise to new club-shaped sw^ell- 

 ings, so that the whole obtains a more or less dense 

 arborescent appearance. These club-shaped enlarge- 

 ments are composed of a resistant membrane and 

 clear contents ; occasionally the membrane shows 

 circular depressions which seem to divide the body 

 into small cubical elements, and at these points trans- 

 verse division is readily j)roduced. 



Besides the typical actinomyces just described 

 there are others which are quite small and in which 

 the enlargements are absent, and others, again, in 

 which the filamentous central zone seems to be en- 

 tirely transformed into these club-shaped elements. 



In colonies of large size the central zone contains 

 micrococci, appearing like small round points of less 

 than 1/1 in diameter, united in chains, or, more fre- 

 quently, in small irregular masses ; these nests of 

 micrococci, in the largest tufts, are not infrequently 



