158 BACTERIA IN RELATION TO PLANT DISEASES. 



Concerning this classification it should be pointed out that large groups of bac- 

 teria are omitted altogether, namely, those which produce neither endospores nor 

 arthrospores. This, so far as we yet know, includes nearly all the plant parasites. 

 About one-half of the genera were hypothetical at the time the paper was published, 

 i. e., not founded on any organism, as I have already pointed out in another place.* 

 The question of whether an endospore-bearing rod is or is not swollen around the 

 spore is often difficult to determine, and as Migula and L/ehmann & Neumann have 

 pointed out, the endospore-bearing rods in some species may be either cylindric or 

 spindle-form, or bear the spores in the middle or at one end. The whole question of 

 the existence of arthrospores is still a matter of doubt. Closely-related forms, and 

 even the same species, may possess one or several polar flagella. The genus Bacillus 

 was founded by Colin on Bacillus subtilis, which is now known to have peritrichiate 

 flagella, Bacillus ulna, also actively motile, and B. anthracis, which is non-motile. 

 Inasmuch as Cohn's studies were made chiefly on B. subtilis, he having never 

 studied B. anthracis, but only including it as a sort of afterthought, for the sake of 

 completeness, and because Bacillus subtilis is the first one described, it seems only 

 proper that the term Bacillus should be restricted to motile forms resembling the 

 hay bacillus, z. e., those having diffuse flagella, and should not be transferred to the 

 non-motile forms. For the hay bacillus and similar forms Dr. Fischer has used the 

 name Bactridium. This name, however, is inadmissible because preoccupied and 

 that, too, whether bacteria be considered as plants or animals. Bactridium has been 

 used as a genus name seven times, as follows : 



Bactridium Kunze, 1817: For fungi, n species of which are recognized in 

 Saccardo's Sylloge Fungorum. 



Bactridium Salisb., used in 1839 as a sectional name under Erica (DC. Prod.), 

 and also in 1889 by Drude in Engler & Prantl's Die Natiir. Pflanzenfamilien. It 

 is said by Baillon to be a synonym of Syringodea Benth. Bentham reduced Don's 

 genus Syringodea to a section of Erica. 



Bactridium LeConte, 1861: Col., p. 86 MS.; Bactridium Sauss.,i863, Orthop. M. 

 Scudder : Genera in Zoology. 



Bacteridium Davaine, 1868 : For the organism causing anthrax. 



Bactridium Schroeter, 1872 : For Micrococcus prodigiosus and various other 

 pigment-bearing bacteria, most of which have since been included under Bacillus. 



Bactridium Fischer, 1895 : For Bacillus subtilis, B. megaterium, B. typhosus, 

 etc. ; B. typhosus, however, being non-sporiferous, so far as known, has logically no 

 place in Fischer's original classification, as already pointed out, since the mere fact 

 of the absence of endospores does not presuppose the existence of arthrospores. 

 The same remark applies to Bacillus amylovorus and to many other species. 



Dr. Fischer himself knew of the existence of Kunze's genus Bactridium, and 

 refers to it, but he does not appear to have known of Davaine's use of the word for 

 the anthrax organism. He thinks that Kunze's "rare, little-known fungi" are so 

 different that there will be no confusion, and insists on using the word with an 

 entirely different meaning for the most curious of all reasons, viz, "um die Harmonic 



*Review in Am. Naturalist. 



