446 



Journal of Agricultural Research 



Vol. XIII, No. 9 



it is capable of producing a spot which, although not resembling pox, may 

 penetrate equally deep in the host tissue. This species of Actinomyces 

 was isolated from sweet-potato material in Delaware, as well as from 

 specimens grown in Texas. Cultures of the organism were grown on 

 various media, and parallel with a strain oi Actinomyces chromogenus 

 from the Irish potato secured through the kindness of Dr. W. J. Morse, 

 of the Maine Experiment Station. The two organisms appeared to be 

 distinct, and it was thought that the species of Actinomyces growii on 

 sweet potato was a new one, to which the name "Actinomyces poolensis, 

 n. sp." was given. Upon submitting a culture of this sweet potato 

 organism to Dr. H. J. Conn, of the Geneva Experiment Station, it was 

 also pronounced by him to be a new species. A. poolensis and A. 

 chromogenus were grown parallel on numerous culture media in plates 

 and on slants. The greatest differences are observed when the two 

 organisms are grown on potato plugs, corn-meal agar, and on Cook's 

 media No. 2} The difference between the two organisms may be sum- 

 marized as follows : 



Media No. 2 slants . . . < 



AntinoTnyces chromogenus. 



Media colored from brown to 

 black. Growth rapid. 



Thick rays, ruffled white. 

 After six weeks, growth 

 slackens, surface becomes 

 brownish. 



Media not darkened . Growth 

 scant, ingrown in substrata 

 but wavy. Color partially 

 white to gray. 



Potato blackened, growth 

 slow, but abundant, spread- 

 ing, raised, wavy, glisten- 

 l ing. 



A pure culture of Actinomyces poolensis was also submitted to Dr. 

 S. A. Waksman, of the New Jersey Experiment Station, who reported as 

 follows : 



Your second culture, "Pox from sweet potato," has also been isolated by us from 

 several soils. As far as I am aware, this organism has not been described as yet. 

 In a series of biochemical investigations on Actinomyces this organism was found to 

 possess strong proteol3i;ic activities, which may perhaps ser\^e as a clue to its patho- 

 genicity. The cultural characters of this organism are as follows: 



A very good growth is produced on different organic media and also on synthetic 

 media containing glucose or glycerine. A good, but uncharacteristic gro%vth was pro- 

 duced on Lubenau's egg medium, Petro£f 's medium, glycerine, beef infusion agar and 

 Leoffler's blood serum. Growth restricted, cream colored, aerial mycelium gray to 



Com-meal-agar slants 



Potato plugs . 



A.ctinom,yces poolensis. 



No color produced in media. 

 Growth slow, thin, flat to un- 

 dulated up to six weeks after 

 which it becomes more abun- 

 dant than in A . chromogenus. 

 Creamy, glistening, becom- 

 ing dirty-cream with age. 



Media not darkened. Growth 

 abundant, flat, deeply in- 

 grown in substratum. Yellow 

 border with raised white cen- 

 ter. 



Potato not colored. Gro\vth 

 slow, thin, wavy, light brown 

 jelly-like, not glistening. 



1 Water (distilled) 1,000 c. c, agar 15 gm., glucose 20 gm., peptone 10 gm., dipotassium phosphate 0.35 

 gUL, magnesium sulphate 0.2s gm. 



