808 EXPERIMENT STATION RECORD. 



In these experiments it was found that anaerobic bacteria developed abundantly 

 on slant agar preparations and on the surface of plate cultures in the presence of 

 hydrogen or any space which is free from oxygen. In the presence of oxygen anaero- 

 bic bacteria develop in mixed cultures with aerobic bacteria, but are notable to develop 

 in the presence of dead aerobic bacteria or any liltrate from a bouillon culture of 

 aerobic organisms. The maximum quantity of oxygen in which the growth of obli- 

 gate anaerobic bacteria takes place is about 0.0031 per cent, and the minimum air 

 pressure suitable for the growth of obligate aerobic forms ajipears to be exceedingly 

 low. Bacterial organisms multiply rapidly in nutrient media. The media then 

 becomes impoverished and finally spore formation occurs. Continued active growth 

 under favorable conditions never brings about the formation of spores. The primary 

 cause of spore formation is lack of nutritive material. In addition to this lack of 

 nutritive matei'ial, oxygen plays an important part in the spore formation in bacteria. 

 Facultative and obligate anaerobic bacteria produce spores rapidly in the presence of 

 oxygen. The S[)ore formation of anaerobic bacteria after the admission of air takes 

 place rapidly under otherwise favorable conditions, even when an abundani'e of 

 nutritive material is still present. Aerobic; bacteria never produce spores in an atmos- 

 phere of hydrogen and under an air pressure of less than 30 mm. The formation 

 of spores takes place most rapidly in nutrient media which are unfavorable to the 

 growth of the bacteria in (juestion. The optimum amount of common salt for spore 

 formation in anaerobic bacteria is about 0.25 to 0.5 per cent, and of grape sugar 5 to 

 10 per cent, while the optimum temperature varies from 34 to 38° C. During the 

 author's experiments it was found that anaerobic bacteria possess a much lower resist- 

 ing power against acids than against alkalis. The formation of spores takes j^lace 

 more readily in a dark room than in diffuse sunlight. 



Differential diagnosis of various micro-organisms belonging to the group of 

 hemorrhagic septicemia Avith the help of specific serum reactions, O. Vcxjes 

 {Centbl. Bakt. u. Par., 1. Abt., 31 {1902), No. IS, Orig., pp. 645-650).— The diseases 

 belonging to the general group of hemorrhagic septicemia are classified by the author 

 into 4 sections, viz., Schweinepest, hog cholera, swine plague, fowl'cholera, and rab- 

 bet septicemia. It is maintained by the author that the serum reaction is normally 

 specific for each of these diseases. It was found that no serum could be obtained 

 which was specific for hog t-holera and swine plague at the same time. 



Unknown infection material, E. Joest {(Anitbl. Bali. n. Par., 1. Aht., 31 {1902), 

 Nus. 8, CJrig., pp. 361-384; 9, pp. 410-422). — The author reviews the literature of the 

 subject in a critical manner, in connection with an extensive bibliography. Esjiecial 

 attention is given to a discussion of those diseases of which tlie nature of the virus is 

 not understood. These include smallpox, foot-and-mouth disease, rinderpest, rabies, 

 mosaic disease of tobacco, etc. A classification of infectious itaterial is adopted in 

 which different kinds of virus are arranged as follows: Living infectious material, 

 including micro-organisms which may in turn be morphologically demonstrable and 

 inay be cultivated; these include bacteria, protozoa, and other vegetable and animal 

 microparasites. This general group of micro-organisms also includes those wliich 

 are not known morphologically and can not be cidtivated; this subgroup includes 

 micro-organisms which can be seen by the aid of the microscope, but have not yet 

 been identified definitely as a cause of disease, and also micro-organisms which are so 

 minute as to be beyond the limits of visibility under the microscope. Besides micro- 

 organisms, the group of living infectious material includes the so-called living, fluid 

 contagium. Chemical infectious materials are considered by the author under the 

 head of intoxication material. It is argued that a strictly infection material and 

 intoxication material are fundamentally different substances and that no mere toxin 

 is capable of producing disease which can be communicated from one animal or plant 

 to another. 



