238 THE AMERICAN MONTHLY [October, 



portions there was scarcely any disease. The plants attacked stop 

 growing, become yellow, dark slimy spots appear on stalk, leaf, and 

 root, and then they soon die. Microscopical examination of the dark 

 slimy masses, which occur within and without the plant, shows that 

 they contain a large quantity of rod-shaped bacteria and others of a 

 spheroidal shape, both varieties being of one and the same species. 



These bacteria were found to develop easily at ordinary temperatures, 

 but above 36° C. their growth ceased. At first independent motion 

 was seen, but later observations failed to verify this. They do not 

 liquefv gelatin. 



In fliiiel media the individual elements are larger than in solid media. 

 Their breadth is about 0.65,'/, and they vary in length from o.S to 1.6//. 

 Spore-formation was never observed. — University of Illinois Agri- 

 cultural Experi7ne7it Station^ Champaign^ i88g^ Bull. No. (5, pp. 

 16^-73; Cf. Centralbl. f. Bakteriol . u. Parasitenk..,\\\ (1890), pp. 

 70-71'; J. R M. S., April, 1890, p. 226. 



Microbic Products which favor the Development of Infec- 

 tion. — Mr. G. H. Roger finds that bacterial secreta have partly poison- 

 ous, partly vaccinative properties. There are, therefore, among these 

 some which favor the development of certain viruses. This latter 

 phase has been observed by the author in the bacillus of symptomatic 

 anthrax. This bacillus, which by itself is harmless to rabbits, speedily 

 kills them if another microbe be injected along with it. This can be 

 done with Staphylococcus pyogenes aureus., Proteus vulgaris., and 

 especially with Bacillus prodigiosus. 



A similar result can be obtained from the anthrax bacillus itself. 

 For if the serum from an anthrax tumor be deprived of its cell-elements 

 by means of a porcelain filter, 4 to 5 ccm. per kilo, of live weight can 

 be injected without harm, while i to 1.5 ccm. coupled with the anthrax 

 bacillus quickly kills. The morbid predisposition induced by such a 

 procedure is, however, of short duration, lasting not more than twenty- 

 four hours, after which the animal again becomes refractory. Hence 

 it would seem that a vaccinative effect is preceded by a period of 

 diminished resistance to the virus. 



Another observation showed that the anthrax bacillus did secrete 

 products favoring its development ; for while the virus, if injected into 

 the thigh, was powerless, the same virus was found to be fatal if in- 

 jected into the anterior chamber of the eye at one and the same time. 

 Hence the products of the latter injection must havearrested the immunity 

 in the muscles, and accordingly it may be concluded that the resistance 

 of animals to infectious diseases can be efiected by harmless as well as 

 by pathogenic bacteria. — Cointes Rendus, cix (1S89), p. 192; Cf. 

 Centralbl. f. Bakteriol. u. Parasitenk.., n\\ (iS9o),pp. 60-61 ; y. 

 R. M. S., April, 1890, p. 229. 



o 



Washington Microscopical Society. 



lOjth Meeting., May 27. — The following was the program for the 

 evening : Exhibition of Class Microscope, with remarks on its use 

 with beginners in zoology and botany, by Mr. Richard Foster. 



Exhibition of some " home-made accessories : " bulls-eye lens, warm 

 stage, eye-shade, catalogue-holder, by Mr. L. M. Mooers. 



