266 



FIXATION OF FKKK MTROOFN HV BA( TFKIA 



of F. NOBHE, K. SriLMiD, L. HILTNER, and E. HOTTER (II.), the nodule bacteria of 



dillt;r greatly from those of Leyuminosce. 



These observations arc also of importance to practical agriculture. Already, 

 for several yem-s past, soils intended to be brought under cultivation (e.g. high 

 moorland soils) for the growth of nitrogen-collecting plants are previously 

 inoculated, />. strewn with a little earth from fields that have borne leguminous 

 plants for a long time, and are consequently rich in nodule-forming bacteria. 

 For this inoculation to have the desired result, it is necessary to use earth 

 containing the bacterial species most efficient for the kind of Leyuminosce to be 

 afterwards grown. Practical experience on the importance of this consideration 

 is already available. Thus SALFELD (I.) has reported that a similar soil intended 

 for peas could not be rendered capable of yielding a crop unless strewn with a 

 little soil obtained from a good pea-field, soil from a lupin-field failing to produce 

 the desired effect. A similar discovery was made by M. FLEISCHER (I.). This 

 treatment must, of course, be preceded by any improvement found necessary in 

 the chemical composition of the soil. Thus, for example, sour moorland must 

 previously be limed, in order to neutralise the acids preventing the development 

 of the nodule bacteria. Moreover, this operation must be performed with 

 discretion, an excessive addition of lime being avoided. Reference may be made 



on this point to a communication by TA< KK. 



IMMEN T DORF, HESSENLAND, SCUUTTE and 



MINSSEN (I.). 



***' / 



5r^/ 



195. The Bacteroids. 



The bacteria in question are often met 

 with in air and water, and very frequently 

 in the soil. NOBBE, SCHMID, HILTNER, and 

 HOTTER (I.) made several quantitative bac- 

 teriological investigations on this point. The 

 bacteria pass from the soil into the roots of 

 such plants as will admit them. The first 

 successful, artificial production of nodules 

 by the aid of pure cultures was made by 

 A. PRAZMOWSKI (IV.). This worker, in 

 view of the absence of the sporogenic 

 faculty in these organisms, changed the 

 name of Jlacillus radicicola, bestowed on 

 them by Beyerinck, into Bacterium rurfiri- 

 cola. According to his observations, this 

 fi.-sion fungus penetrates the epidermal cells 

 of the root-hairs, and there develops to a 

 colony which then surrounds itself with a 

 tough membrane. From this original posi- 



tum then, brad*, out a lustrous ^ K\\\ 



it- iiiii-irniis (lyin- in ;i vsiruoii-) : /. tin- \\ith bacteria, which turns towards the bark 

 iiif.rtini.-iim-sHs: //. Hi- nfcroMmiei of C( . 1|s <an( | ) (r;llic .hes out amongst them. As 

 tin- cytoplasm* ; "//'. >t;irdi grannies; /. . . . , ' , , 



];,r^.-'-,-ntr:ii wnotoi bact. UK- i,(M.-n.i.is. a result of this advance towards the centre 

 \fter /;< // ////</.) of the root-hair, the cells thereof are incited 



to rapid increase and become densely 



crowded, in consequence of which they assume a polygonal outline, and constitute 



the bacteroidal tissue already mentioned (Fig. 62). The plasma of these colls, 



with its fungoid enclosures, has been termed mycoplasma by A. B. FRANK (VI.). 



Before tracing the career of the bacteria any further, a few explanatory 







j. Section tliroii-li tin- l.;irtcmi<l;il 

 Liitliyrus >ylvc-ms. 



