VETERINARY SCIENCE AND PRACTICE. 1127 



tective envelope which aids it in its passage to the new host, The formation of pro- 

 tective coverings, the strengthening of the cell wall, and the secretion of defensive 

 fluids will account for the well-known phenomena in bacteria better than the current 

 theory according to which parasitism is based exclusively on the production of toxin. 



According to the nature of the diseases produced by different micro-organisms, 

 these bacteria may be divided into 3 groups in the first of which are placed bacteria 

 which live upon the skin and mucous membranes and gain entrance to the body 

 only through lesions; the second group appear only occasionally and produce 

 epidemics, while the third group are best adapted for parasitic life and produce 

 diseases of a fixed type. The organisms of diphtheria and pneumonia belong to the 

 first group, those of Asiatic cholera and bubonic plague to the second group, and 

 tuberculosis, leprosy, glanders, and the eruptive diseases to the third group. 



Progress in bacteriology, Busch and G. Marpmann (Ztschr. Angew. Mikros., 10 

 {1904), No. 8, pp. 197-207). — Attention is called to the great importance in modern 

 bacteriology of the relationship between pathogenic bacteria and host. The biology 

 of these bacteria is briefly discussed with notes on the chemical substances produced 

 by their action. 



The effect of filtration on bacteriolytic complements, Edna Steinhardt 

 (Jour. Med. Research, 12 [,1904), No. 4, pp. 479-489).— The chief " purpose of the 

 investigations reported in this paper was to determine the effect on the bacteriolytic 

 complement of passing serum through a Berkefeld filter. The author also attempted 

 to devise a method for separating the bacteriolytic complement from the immune 

 body at a temperature of 0° C, and also to differentiate different bacteriolytic com- 

 plements by filtration. 



In these experiments it was found that horse serum when passed through a 

 Berkefeld filter of the smallest size and finest quality lost the bacteriolytic comple- 

 ment until the filter became saturated by absorption, after which the complement 

 passed through without apparent loss. It was found possible to separate the bac- 

 teriolytic complement from the immune body at a temperature of 0° C, but the 

 method is attended by so many technical difficulties as to render the results 

 obtained rather uncertain. 



The differentiation of bacteriolytic complements by filtration is, in the author's 

 opinion, to be explained by their quantitative differences in the original serum 

 rather than by a difference in the size of molecules or a difference in the adhesive- 

 ness of the molecules of several complements. 



The influence of artificial interference with metabolism upon the produc- 

 tion of alexins, P. T. Muller (Arch. Hyg., 51 (1904), No. 4, pp. 365-421).— In the 

 course of most infectious diseases during which a crisis occurs it has been observed 

 that the favorable or unfavorable turn which may take place at this time is influenced 

 in a large degree by the relative amount of alexins produced by the affected animal. 



With this fact in mind, the author undertook a number of experiments for the 

 purpose of testing the influence of artificial changes in metabolism upon the course 

 of infection. Pigeons were subjected to a period of fasting and then inoculated with 

 a number of pathogenic organisms including the bacilli of typhoid, dysentery, Bacil- 

 lus proteus, etc. The withholding of food from pigeons was found to influence the 

 production of agglutinins in a striking manner. This influence differed, however, 

 in the case of different micro-organisms. After infection with certain species of 

 bacteria the quantity of agglutinins was increased, while in other cases it was dimin- 

 ished. 



A test was also made of the influence of the kind of nutrition upon the course of 

 infectious diseases. Pigeons were used in these experiments and were inoculated 

 with Bacillus pyocyaneus or B. proteus. Some of the pigeons were fed with milk, 

 wheat bread, and potatoes, while others received no milk. The kind of nutriment 

 received appeared to have no influence upon the immunization of the pigeons toward 



