igig] DRECHSLER— ACTINOMYCES 67 



verse walls may appear with somewhat greater frequency, there are 

 none in which septation approaches any pronounced degree of 

 regularity or closeness. Ramifications are abundant, and the 

 branching is altogether of the ''true" type. Mace (15), who first 

 carefully observed the formation of branches, found it to proceed 

 by the elongation of lateral buds arising some distance back from 

 the growing point of an axial filament, the branch thus produced 

 giving rise similarly to secondary branches by lateral proliferation. 

 Lachner-Sandoval (12) confirmed Mace, designating the process 

 as monopodial and denying the existence of true dichotomy in the 

 genus, which had been affirmed by previous investigators. Later 

 Neukirch (18) reported that the branching in Actinomyces ochro- 

 leuceus was occasionally of the nature of a true dichotomy. From 

 an examination of very young mycelium (fig. 3)^ it is apparent 

 that, at least in stages following the germination of the spore, 

 filaments are not infrequently terminated by two elements too 

 closely similar in size and angular relationships to be distinguished 

 as bud and axial tip. The branching in such cases must be regarded 

 as dichotomous, although all gradations toward the prevailing well 

 defined monopody may be found. It seems reasonable to suppose, 

 however, that the distinction is one of convenience, not implying 

 any fundamental difference in, manner of development. 



The cytological structure of Actinomyces is equally devoid of 

 bacterial characteristics. The branches forming the periphery of 

 the actively growing pellicle, or the young sporogenous branches 

 attached at intervals to the superficial mycelium, are iilled with 

 dense protoplasm, which, with haematoxylin, takes a deep homo- 

 geneous stain. Further toward the origin of the hyphae the con- 

 tents become more attenuated, and vacuoles appear, increasing in 

 number and size until they occupy the larger portion of the fila- 

 ments. When individual vacuoles become excessively large and 

 extend through a considerable length of filament, the cytoplasm 

 is in a large measure confined to a peripheral layer, a condition 

 which led Neukirch to distinguish a thin, strongly refringent 

 "Aussenplasma" and a less refringent "Innenplasma." 



3 The plates will appear in connection with the second part, to be published in the 

 following number. 



