1348 Journal of Applied Microscopy 



being prevented from growth by the presence of the smallest amount of organic 

 material or ammonia. In previous work Stutzer has taken grounds quite in 

 opposition to many of the points which were held by Winogradsky. The present 

 article is practically a withdrawal on the part of Stutzer of all of his previous 

 claims. In an introduction he explains how, in the press of engagements, he 

 was led into error by leaving the work to an assistant, and he now reports the 

 results of more careful work. In practically all respects Stutzer now agrees 

 with Winogradsky, so that the relation of the nitrifying bacteria to the various 

 conditions of nature which had previously been so carefully described by 

 Winogradsky, must be taken as confirmed by this latter work of his opponent 

 Stutzer. Stutzer studies both the nitrate and the nitrite forming bacteria, and 

 in most respects comes to identical conclusions with those of the Russian 

 bacteriologist. h. w, c. 



Hiltaer. Ueber die Ursachen, welche die As is well known, all species of leg- 

 Grosse, Zahl, Stellung und Wirkune der . . ,. ., vi i 



Wurzelknollchen der Leguminosen bedin- "^es growmg m ordmary soil are likely 

 gen. Cent. f. Bak. u. Par. II, VII, p. to develop tubercles on their roots 

 "°^' ^^ ■ through the agency of bacteria. Out- 



side of the family of legumes only three or four families of plants are known to 

 produce similar tubercles, and these only in exceptional cases. The author 

 raises the question as to the reason why the soil bacteria have this power of 

 growing in the roots of legumes. Thinking that it was possible that the organ- 

 isms produce some secretion which affects the roots of the legume, he instituted 

 experiments, the result of which was to show him that : (1) the changes in the 

 root hairs of the legumes accompanying the production of a tubercle are 

 produced by some soluble substance secreted by bacteria ; (2) this substance is 

 present in great quantity in the tubercles ; (3) the older root hairs are immune 

 against the action of this substance. 



The author finds that different cultures of the tubercle organisms have 

 considerable difference in their power of producing tubercles. When a plant 

 which already possesses tubercles is inoculated with culture of a bacteria of a 

 higher virulence, it is noticed that there is a very considerable increase in the 

 number and size of the tubercles. If, however, a plant possessing tubercles is 

 inoculated by a culture of the same virulence there is no increase of number of 

 tubercles. In other words, according to the author's conclusions, the presence 

 of the tubercles renders the legume immune against the further action of cul- 

 tures of the same grade of virulence, although they are not immune against a 

 culture of a higher virulence. h. w. c. 



„. . . , . . ,. . ,. , .. The authors investigate a somewhat 



Piorkowski and Jess, r.actenum coli als Ur- ° 



sache eines seuchenartigen Fferdesterbens unusual epidemic among horses occur- 

 in Westpreussen. Cent. f. Bac. u. Par. I, j-ing in West Prussia, and causing the 

 XXIX, p. 285, 1901. ^ ' ° 



death of quite a number. The disease 



was accompanied by fever and intestinal troubles, and lasted from two hours to 

 eight weeks in different cases. Post mortem examination showed the presence 

 in the intestines, of ulcers which had a tendency to perforate the wall. Bacter- 

 iological study of the infected parts showed exceptionally large numbers of a 



