19 1 9] DRECHSLER— ACTINOMYCES 79 



24, 25). Later the unsegmented portion is gradually evacuated 

 and converted into a sterile stalk devoid of protoplasm (figs. 29, 

 30). It is interesting to note that the basal septum, which in an 

 allied and very similar form, Actinomyces VI, delimits the lowest 

 spore from the axial filament, here also is present as a well developed 

 cross- wall. 



The delimitation of the ultimate cells in the process of sporula- 

 tion occurs usually as the growth in thickness and the contraction 

 of the spiral (where this is present) are approaching a stage of 

 completion. It has usually been believed by investigators that the 

 details connected with spore formation are uniform throughout the 

 genus. This belief, which the writer was at first inchned to share, 

 must be considerably modified in view of the diversity of conditions 

 actually found. In most species the sporogenous h>phae become 

 divided into regular cylindrical cells separated by septa; the latter 

 generally stain deeply with Delafield's haematoxylin, probably as 

 the result of an association with metachromatic or possibly nuclear 

 material. The species which are thus characterized by clearly 

 defined septation may be assigned to three different categories, 

 separated by differences in the disposition of their septa and in 

 the development of their spores. 



In the first category, represented by Actinomyces I, the cross- 

 walls in the sporogenous h)q)hae remain without any very pro- 

 nounced change, continuing to separate the adjacent cells until these 

 have developed into a chain of mature contiguous spores. The 

 insertion of these septa progresses from the tip toward the base, 

 and does not break the physiological continuity of the hyphae; 

 for food material apparently is readily transported through them 

 to the young spores at the termination, since these subsequently 

 increase in size, and may deposit a wall of measurable thickness. 



In the second category the septa apparently split into halves, 

 which are then drawn apart by the longitudinal contraction of the 

 individual protoplasts (figs. 5CI, 8a-/, 59). In Actinomyces II 

 the very pronounced growth in thickness of the sporogenous hyphae, 

 following the insertion of septa, indicates that in this species also 

 septation brings about no impediment in the transfer of food 

 material. This is particularly remarkable on account of the 



