and Laboratory Methods. 1141 



different strengths (.8 per cent, to G.O per cent.) seems to depend quite exactly 

 on the number of molecules of salt which strike the animal in a unit of time. 

 The relation of time of killing and strength of solution is represented by the 

 rectangular hyperbola y(x — 8) =277. An increase in temperature causes the 

 molecules to move faster and strike with greater momentum, and hence the time 

 of killing is reduced in high temperatures. The physiological condition of the 

 animal is a most important factor in determining its power of resistance to NaCl. 

 Perhaps the most striking result of the investigation is that animals which have 

 become acclimatised to a .25 per cent, salt solution show less resistance capacity 

 than do normal, unacclimatised specimens, to solutions of greater concentrations. 

 The author thinks that this is probably due to some constitutional weakness 

 resulting from the acclimatising process. Daphnia living in a confined volume 

 of water were shown to have shorter caudal spines, and to reproduce less vigor- 

 ously than those that had lived in an unlimited bulk. Water in which Daphnia 

 has lived for some time has a poisonous effect on individuals from other cultures. 

 This paper is of interest in connection with the recent work of Miss Enteman 

 (Amer. Nat. 34 : 879-890) on the extreme variability of a related species Daphnia 

 hyalina under differing natural environmental conditions. R. p. 



CURRENT BACTERIOLOGICAL LITERATURE. 



H. W. Conn. 



Separates of papers and books on bacteriology should be sent for review to 

 H. W. Conn, Wesleyan University, Middletown, Conn. 



Flexner. The Etiology of Tropical Dysentery. The author has made an extensive 



Cent. f. Bac. u. Par. I, 28 : 625, 1900. • r i. j- r j 



^ series of studies of dysentery occurring 



in the Philippines, and comes to the conclusion that dysentery is of two distinct 



types. One, the chronic form, is accompanied by the presence of amoebae in the 



intestines in large quantities, and is, therefore, what has been called amcebic 



dysentery. The other, the acute form, is not accompanied by these protozoa, 



and appears to be produced by bacteria. The author finds universally present 



in these cases, a bacillus which he describes and with which he experiments. 



This bacillus is pathogenic for small animals, producing symptoms quite similar 



to those of dysentery, and is believed by the author to be unquestionably the 



cause of acute dysentery in eastern countries. The organism is identical with 



that isolated by Shiga from the epidemic of dysentery prevailing in Japan. 



Flexner regards this cause of dysentery as widely distributed in nature. 



H. W. C. 



Ritchie. The Bacteriology of Bronchitis. The author makes a bacteriological 



Jour, of Path, and Bact. 7: i, looo. ^ i r i. r r l 



■' ^ Study of a number of cases of bron- 



chitis. In most instances they were made by post mortem examinations, and 

 were bacteriological studies of the lung tissue. Numerous bacteria are found in 

 the lungs under the circumstances, most of which, as would be expected, have 

 nothing to do with the disease. The general conclusion of the author is as 



