NOTES AND ABSTRACTS. 



127 



Bacteria and Leguminosae (U.S.A. Dep. Agr. Bur. PI. Ind., Bulls. 

 71 and 72 ; Farmers' Bull. 214 ; Exp. Stn. Oklahoma, Bull. 68 ; Neiv 

 York, Geneva, Bull. 270; Virginia, Bull. 154; Michigan, Bulls. 224 

 and* 225).— The practice of inoculating seed or soil with cultures of 

 bacteria capable of producing nodules on the roots of leguminous plants 

 is becoming more and more widespread. Experiments seem to show that 

 only one species of micro-organism (Psendomones radicicola) is concerned, 

 and that there are many races the differences between which can be 

 readily broken down by cultivation. The new method of cultivation 

 devised by the American Board of Agriculture experts on media free from 

 nitrogen ensures the infective power of the bacteria being undiminished. 

 Various external conditions, such as heat, moisture, alkalinity, amount 

 of nitrogen in the soil, and so on, all influence the development of the 

 bacteria. The view is taken in the first of the publications cited, that 

 the bacteria which invade the tubercles are dissolved and absorbed by the 

 plant, and it is only the branching forms of the bacterium which are 

 capable of being overcome by the plant and destroyed to its benefit ; the 

 rod forms are not able to be dissolved by the host. The relationship 

 between the bacillus and the leguminous plant is precisely that between 

 a parasite and its host. An interesting point discovered is that nitrogen- 

 fixing bacteria are able to penetrate the roots of plants, and be of decided 

 benefit, without the formation of nodules or any external evidence of 

 their presence : this was found to be the case in soy beans and lucerne. 

 Inoculation, it is pointed out, can only be of benefit when the soil does not 

 already contain the particular bacteria, although there are some exceptions 

 to this rule ; and where a soil is very rich in nitrogen the development 

 of nitrogen-fixing organisms is inhibited. "Inoculation is necessary — 

 (1) on a soil low in organic matter that has not previously borne 

 leguminous crops ; (2) if the legumes previously grown on the same 

 land were devoid of nodules or 1 nitrogen knots,' showing the need for 

 supplying the nodule-forming bacteria ; (3) when the legume to be sown 

 belongs to a species not closely related to one previously grown on the 

 same soil." 



The Oklahoma Bulletin points out that liquid cultures give better 

 results than dried cultures, and that light is fatal to the organisms ; 

 cultures and inoculated seed should therefore be kept in the dark. The 

 New York Experiment Station found that the dried cultures distributed 

 on cotton-wool failed to give satisfactory results ; that they, indeed, 

 contained no living nodule-making germs — a statement corroborated by 

 some other investigators. The Virginia Bulletin deals with the cultiva- 

 tion of alfalfa (lucerne, Medicago saliva) and the inoculation of the soil 

 with the germ proper to that plant. In Michigan it was found that the 

 plants on which nodules were developed were much richer in protein 

 than those from which they were absent, and this was true, not only of 

 the growing plant, but also of the seed produced by it. — F. J. C. 



Bacterial Rot, A, of the Potato caused by Bacillus solanisapms. 



By F. C. Harrison (Centralblatt fiir Bakteriologie, Parasitcnkundc und 

 Infektionskrankheiten, Abteilung ii. Band xvii. 1906). — The author draws 

 attention to the great confusion which exists among cultivators generally, 



