700 MEDICAL MYCOLOGY 



portion is gradually evacuated and converted into a sterile stalk devoid of 

 protoplasm. 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 septum. 



The delimitation of the ultimate cells in the process of sporulation occurs 

 usually as the growth in thickness and the contraction of the helix are ap- 

 proaciiing completion. It has usually been believed that the details connected 

 with the spore formation are uniform throughout the genus, but this is not 

 universally true. In most species, the sporogenous hyphae become divided 

 into regular cylindric cells separated by septa ; the latter generally stain deeply 

 with Dclafield^s hematoxylin, probably as a result of an association with 

 metachromatic or possibly nuclear material. These species may be subdivided 

 into three groups. 



Fig. 115. — Actinomyces XVIII. Degenerate axial filament containing large vacuoles and 

 spherical structures and bearing a fertile helix (X2,750). (After Drechsler 1919.) 



In the first group (e.g., Actinomyces /), the cross walls in the sporogenous 

 hyphae remain without any very pronounced 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 physiologic continuity of the hyphae, for food material 

 apparently is transmitted through them to the young spores at the termina- 

 tion, since these subsequently increase in size and may deposit a wall of 

 measurable thickness. 



In the second group, the septa split into halves, which are then drawn 

 apart by the longitudinal contraction of the individual protoplasts. 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 remarkable in view of the extraordinary thickness of the septa character- 



