KEY TO GENUS ACTINOMYCES. 439 



white mold. Not infrequently chains of conidia are formed 

 when the culture is submerged in river-water or 4% sugar 

 solution ; yet here the spore chains are copiously branched, 

 and the segmentation may even encroach far upon the 

 threads (Gasperini, Lachner-Sandoval). Also some au- 

 thors describe the occurrence of spore-like formations in 

 the interior of the threads, but we have never certainly 

 seen it. According to Lachner-Sandoval, this is only a 

 fragmentation of the contents of the threads, which must 

 not be interpreted as spore-formation even if it can be 

 demonstrated that such fragments of threads cicatrize at 

 the ends and later grow out again. They are not stained 

 by the T. B. method, but always by Gram's method.* 



Key to Some of the More Important Varieties of the 

 Genus Actinomyces. 



(A) Pathogenic varieties, with clubbed swellings of the ends of the 

 threads in the animal body. Upon artificial nutrient media the for- 

 mation of clubs is rare; conidia are sometimes produced in cultures, 

 sometimes not. 



(a) No growth below 22°, no growth on potato, no air mycelium, 

 formation of clubs in artificial cultures very limited. Pathogenic for 

 rabbits. Actinomyces Hofmanni. (Gruber.) Gasperini. Page 447. 



(6) Grow below 22° and upon potato; formations of clubs in cul- 

 tures scarcely ever observed. 



1. Agar cultures, yellowish-orange, knobby, sometimes with air 

 mycelium. Gelatin slowly liquefied. Typical club-formation in the 

 body. Cause of the typical ray-fungus disease in cattle and man. 

 Actinomyces bovis. Gasp. Page 440. 



2. Agar growth, dry, granular, scanty. Pathogenic for cattle. 

 Clubs have not been demonstrated in the animal. Actinomyces far- 

 cinicus. Gasp. Page 447. 



3. Agar culture, a luxuriant, wrinkled, orange-yellow layer, with 



' For the limitations and naming of this genus, see Lachner-Sando- 

 val, Ueber Strahlenpilze, Bonn, 1898; Sauvageau and Radais (A. P. 

 VI, 242, Sur de genre Oospora) ; and our discussion on page 127. Ee- 

 garding the species, the following articles are also important: Alm- 

 quist (Z. H. VIII, 189, 1890), Gasperini (Annales de Micrographie, Bd. 

 II, 449, 1890), and Annal. dell'Istit. d'Igiene di Roma, II, 1892, 

 166 (C. B. XV, 684). Rossi Doria (Annal dell'Ist. d'Ig. de Roma, 

 Bd. I, 1892, 399). See also Berestnew (Z. H. xxix, 94). 



^ While we ourselves naturally appreciate that this key is not satis- 

 factory, our information does not allow us as yet to prepare a better 

 one. 



