igig] DRECHSLER— ACTINOMYCES • 149 



Morphology. — The development of the erect sporogenous 

 hyphae of this species is strictly successive, and may be followed 

 in the branch d in fig. 2, the younger of any 2 hyphae being dis- 

 tinguishable by its attenuated attachment. The partly disrupted 

 chain of spores di here represents the original prolongation of 

 branch d; the chain d2 represents a secondary branch, the spores 

 here being mature but still retaining their spiral disposition without 

 showing indications of disruption; while dj represents a tertiary 

 branch, in which septation has not commenced. A similar sequence 

 is illustrated in the succession of derivatives bi, b2, bj, and 64 

 from the branch b, as well as in the 5 elements ci-cj associated 

 with the branch c. 



A more complex system of fertile h>'phae is shown in fig. i, but 

 the larger fructifications are probably 10 or even 15 times more 

 extensive, and bear many thousands of spores. The species is 

 characterized by close sinistrorse spirals, of 2-6 turns, and 3-4 /x 

 in diameter, which during the later stages of maturation are relaxed, 

 although indications of them may persist in the flexuous or sinuous 

 course of the mature chains of spores. The mature spores are 

 ellipsoidal, 1-2-nucleated, with a distinctly visible wall and a 

 central vacuole of varying size. They measure i . 2-1 .4X1. 4-20 /x, 

 and upon germinating produce 2-4 germ tubes, which early pro- 

 liferate numerous branches, and show at intervals some dark 

 staining granules. 



Isolated 5 times from soil collected in Cambridge, Massachusetts. 



ACTINOMYCES II 



Cultural chail\cters. — On glucose agar, growth moderate; 

 nutritive mycelium colorless, early covered with a cretaceous or 

 downy aerial mycelium ; pigment absent. On potato agar, develop- 

 ment of nutritive mycelium moderately rapid; aerial mycelium 

 appearing in scattered areas, first white, later becoming slightly 

 discolored; substratum stained yellow by a soluble pigment; 

 tyrosinase reaction absent. 



Morphology. — ^The most conspicuous feature of this species 

 is the extraordinary thickness of the septa (0.3-0.35 fi) associated 



