1 68 BACTERIA IN RELATION TO PLANT DISEASES. 



Bacteria with Fungi. 



In 1903, Zederbauer published a paper on the Myxobacteriaceae, in which he claims 

 that he has demonstrated that certain of these organisms are a symbiotic combination of 

 bacteria and fungi. 



His first investigations were made on a reddish form, which he calls Myxococcus incrustans, 

 growing on sponges used for wetting gummed paper. This form, which looked like a slime mold 

 was made up of bacteria, chiefly, with occasional fungous hyphae, and chains of small round bodies 

 which he thinks were conidia. 



He succeeded in obtaining pure cultures of the bacteria (some of them, at least) on peptone 

 gelatin. At room-temperature, in the light, they grew rapidly, forming a film of branching radiating 

 chains of bacteria on the surface. In rather old colonies these floated for a time on the liquefied 

 gelatin, then sank to the bottom. Growth occurred also below the surface, but was not so luxuriant. 



All cultures, in repeated experiments, produced the same bacterium. The color of the 

 Myxococcus is not shared by the bacteria. The colonies are dirty white. Spores were formed in old 

 cultures. No cilia were demonstrated, nor was the movement like that of ciliated forms. On agar, 

 growth appeared similar to that on gelatin, but the agar was not liquefied. The bacteria did not 

 grow on sterilized bread or potato. 



The fungus was also cultivated separately. Spores taken from the so-called Myxococcus ger- 

 minated in the usual manner, forming several celled hyphae, which soon produced conidia, like the 

 original spores. Mycelium also developed from oidia which were formed by the breaking up of 

 filaments. 



Although Zederbauer thus cultivated both fungus and bacteria separately, he did not succeed 

 in reproducing the original mixture, the Myxococcus, by growing them together. 



Cysts, he states, like those described by Thaxter, were found. These were composed of bacteria 

 and chains of conidia surrounded by a common envelope, probably composed of hardened slime 

 secreted by the bacteria. On germination, this bursts and the new organism begins growth. 



The color of his Myxococcus is not constant. It may be red, pale yellow, and sometimes black. 



A form which he calls Chondromyces glomeratus was found in several localities growing in groups 

 upon the cut surface of beech stumps which had not begun to decay. The slimy red outgrowths 4 to 

 5 mm. high, resemble Tremella. This form he says was also composed of bacteria and fungous hyphse. 

 The long slender hyphae, rising from spores at the base, intertwined and formed at the surface a 

 thicker layer of conidiophores bearing chains of conidia. The very small rod-like bacteria which 

 swarmed in the interior were actively motile. 



Several conidia were germinated in a moist room, forming hyphae, which, however, did not 

 produce conidiophores. 



The bacteria, which stained with methylene blue and fuchsin, grew on gelatin and agar. On 

 gelatin plate cultures at room temperature or in the thermostat at 2oC, small dirty white drops 

 were formed which united and liquefied the gelatin in hollows. In cultures kept near the window, 

 growth was strongest near the light. Streak cultures behaved very much like plate cultures. The 

 bacteria did not liquefy agar but formed over the whole surface a dirty white layer, starting from 

 small round flecks. All cultures were fluorescent. 



The flagella, attached to all parts of the body, were stained with Van Ermengem's stain as modi- 

 fied by Hinterberger. In some cases they were ten times the length of the bacteria. Spore formation 

 was not observed. 



In gelatin cultures when hyphae were brought in at the point of inoculation they took on irre- 

 gular shapes and seemed to form conidia. Chlamydospores were also formed in such cultures. 



Zederbauer claims that the origin of these demonstrates that they are fungous spores and not 

 bacteria as claimed by Thaxter. 



The first part of this paper is devoted to speculations on whether Thaxter's statements and 

 figures can be interpreted as indicating the presence of mycelium in the Myxobacteriaceae. There 

 seem to be a good many uncertainties connected with his own researches. 



Dr. Thaxter's comment on this paper is as follows: 



"This treatment of the group, though novel, seems somewhat hasty; especially in view of the 

 fact that the figures and descriptions given in this paper show very clearly that its author is as yet 

 unacquainted with any member of the order he discusses, having been misled by fancied resemblances 

 and influenced no doubt by an exaggerated notion of the difficulties associated with the differentia- 

 tion of rod-like bacteria from Oedocepkalum, Torula, and similar hyphomycetous types. A specimen 



