68 BOTANICAL GAZETTE [january 



The presence of large vacuoles is commonly associated with 

 local distentions of the filament wall. These may occur with such 

 regularity in the degenerate mycelium of some species as to suggest 

 the appearance of Leptomitus, each swollen segment being largely 

 occupied by a single elliptical vacuole, separated from the vacuole 

 in the adjacent distention by a protoplasmic partition at the con- 

 striction (figs. 47, 48, 106). In other species and quite generally 

 in the nutritive mycelium of all forms, that is, the mycelium im- 

 mersed in the substratum, no marked regularity in the alternation 

 of inflated portions and constrictions is observable; but pro- 

 nounced deviations in the diameter of filaments may occur with 

 more or less variable frequency. 



A great deal of importance has been attributed by some writers 

 to a variety of abnormalities "and products of degenerative changes 

 occurring in the thallus of Actinomyces. In the earlier literature 

 on the ray fungus, especially in the publications of Israel (8), 

 JOHNE (9), and MacFadyean (16), bodies described as "micro- 

 cocci," "cocci," or "coccus-like granules" were given minute 

 attention, and assigned an important role in the complex ontogeny 

 ascribed to the parasite, then supposed to belong to the pleomorphic 

 bacteria. Wolff and Israel (24), whose photomicrographs of 

 these bodies leave no reasonable doubt about their identity with 

 structures very frequently observed by the writer (figs. 15, 31, 32, 

 42, 91), confused them with the spores reported by other authors; 

 and as the structures did not possess the heat resistance common 

 to spores of bacteria, these investigators were inclined to question 

 the production of spores by Actinomyces. Since the organism 

 used by Wolff and Israel was constantly sterile, their conclusion 

 concerning it was undoubtedly correct. Bostroem, who experi- 

 mented with a sporiferous form, did not succeed in avoiding the 

 same confusion, and refers indiscriminately to the unicellular 

 products formed from aerial hyphae, and to the spherical endoge- 

 nous granules, as "spores." 



Round granules, deeply stained in the living filament by very 

 dilute methylene blue, were studied later by Neukirch. He 

 noted in them a variable size, a method of multiplication, and an 

 orientation related to the regions of growth in the thallus. These 



