and Laboratory Methods. 1587 



Wasmann, E. Nervenphysiologie und Tier- A, criticism of the method of investiga- 

 psychologie. Biol. Centralbl. 21: 21-ti, ,. , . , , , . ... 



jQQj ° tion of animal behavior which centers 



itself in the study of the physiology of 



the nervous system. The author favors the method of comparative psychology, 



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. 



Pierce, Newton B. Walnut Bacteriosis. Bot. Newton B. Pierce, of the U. S. Depart- 

 Gaz. 61 : 272. 



ment of Agriculture, has recently 



described a new organism as the cause of the walnut bacteriosis, giving to it the 



name of Fseudojnonas juglandis. The organism is a short rod with rounded ends, 



actively motile, bearing a single, long, polar, unusually wavy flagellum, occurring 



singly or in pairs, and sometimes in short or long chains. This organism is 



very strikingly pathogenic to the nuts, leaves, and tender branches of the English 



walnut. In the young walnut, the epicarp and forming shell and kernel are 



destroyed. The author has produced a large number of infections by spraying 



the young buds with a pure water culture of the organism. L, H. Pammel. 



Eijkraann. Ueber Enzyme der Bakterien und ^^^^ ^^^^^^^^ ^as experimented upon the 

 Schimmelpilzen. Cent. f. Bak. u. Far. i, _ ^ _ , 



29: 841, 1901. formation of enzymes by bacteria in a 



somewhat ingenious and extremely 

 interesting method. The method consists, in brief, in using agar which has been 

 mixed with a certain amount of material upon which the enzyme to be tested will 

 have a solvent or other noticeable action. For example, he first tested the 

 formation of an enzyme which digested casein. To do this, he mixed a certain 

 amount of fresh skimmed milk with agar, making a white, cloudy liquid, and 

 then inoculated this agar, upon an ordinary plate, with the bacteria to be tested. 

 If the enzyme is produced, it diffuses from each colony and, as it diffuses, it 

 digests the casein so that it dissolves in the liquid present. The result is that 

 the colonies become, in a few days, surrounded by clear fields, which indicate 

 the digestion of the casein. On the other hand, bacteria which do not pro- 

 duce this enzyme do not develop such clear fields. By this means can be de- 

 termined at a glance whether certain bacteria develop the enzyme in ques- 

 tion. The author tested a large number of bacteria, finding that those which 

 liquefy gelatin produce also the enzyme which digests the casein. From this he 

 concludes that the casein digesting enzyme and the liquefying enzyme are 

 identical. 



The author tested the haemolytic power of bacteria by adding to the agar a 

 few drops of blood, thoroughly shaking the mixture, and afterwards inoculated it 

 with the bacteria to be tested, pouring it out upon plates as usual. The bacteria 



