Sericulture. 



[September, 1909. 



seen ; the production of thread and 

 cloth offers no difficulties to people 

 accustomed to spinning and weaving 

 cotton; and there is no inherent difficulty 

 which would prevent its adoption in all 

 parts of India where castor is grown 

 and where the climate is suitable. The 

 culture of the worm on a large scale or 

 its utilisation on a large scale in power 

 looms, is a matter of commercial enter- 

 prise and not our immediate concern. 

 Where castor is available, large quanti- 

 ties could be produced and either spun 

 or woven locally, or collected and 

 utilised in a factory. 



In Behar, the cost of producing the 

 cocoons, spinning the thread, and weav- 

 ing the cloth, totals up to much less 

 than the market value of the cloth, 

 though full wages are paid to the rearers 

 and spinners ; where the rearing and 

 spinning are done by whole families 

 iucluding women and children in their 

 leisure time when field work is not 



pressing, it represents a valuable minor 

 industry. 



At the present time, the seed is obtain- 

 able only from Assam or from Pusa. 

 We would emphasize the very grave 

 danger of obtaining live cocoons from 

 Assam, since they carry the parasitic 

 fly, the most dangerous enemy to the 

 worms ; and, as a rule, seed obtained in 

 the ordinary way from Assam is bad. 

 Good seed will be sent from Pusa, and, 

 if notice is given, a large supply of seed 

 is usually available. A limited number 

 of men, trained to the work, are avail- 

 able for starting the industry in new 

 places, and anyone wishing to learn it 

 can be taught in the Pusa rearing house 

 in a short time. The industry is being 

 taken up in different parts of India, and 

 wherever there is a demand for light 

 remunerative work, such as can be done 

 by women and children, if castor is avail- 

 able, the rearing, spinning and weaving 

 of this silk offer many advantages. 



SCIENTIFIC AGRICULTURE. 



FIXATION OP NITROGEN BY 

 BACTERIA.* 



(From the Gardeners' Chtonicle, Vol. 

 XL V., No. 1172, June, 12, 1909.) 



The fixation of nitrogen by bacteria, 

 though a somewhat well-worn snbject, 

 is one of the most fundamental problems 

 of agriculture, and one which is con- 

 stantly receiving new light from one 

 source or another. Nitrogen is not only 

 an essential element in the nutrition of 

 the plant, but the fertilising substance 

 most costly to purchase, although in its 

 free, gaseous state it constitutes four- 

 fifths of the atmosphere. Our ordinary 

 plants, however, are incapable of draw- 

 ing upon this stock of free nitrogen, 

 and hence they must obtain combined 

 nitrogen from the soil. This fact — the 

 subject of long controversy— may be 

 said to have received its crowning 

 demonstration by the experiments of 

 Lawes, Gilbert, and Pugh at Rothamsted 

 in 1857-8. Despite these and other ex- 

 periments, it became evident that some 

 factor in the situation had been over- 

 looked, because from many sources— the 

 Rothamsted field experiments among 

 others— it was shown that leguminous 

 crops not only took away an exceptional 

 amount of nitrogen, but left the ground 



* Lecture delivered on March 11, 1909, by 

 Mr. A. t>- Hall, Director of the Rothamsted 

 Experimental Station. 



richer in nitrogen compounds than it 

 was before their growth. These diffi- 

 culties were cleaied up by Hellriegel 

 and Wilfarth in 1886-7, when they 

 showed that leguminous plants were 

 susceptible to the infection of an organ- 

 ism which produced nodules upon their 

 roots, whereupon they became able to 

 draw upon the atmospheric nitrogen. 



The nodules contain in vast numbers a 

 bacterium which effects the fixation of 

 nitrogen ; the combined nitrogen is 

 passed on to the host plant, which in its 

 turn supplies the bacteria with the carbo- 

 hydrates they require. The nodule 

 bacteria, which have only latterly been 

 isolated in a pure state directly from 

 the soil, exist in the soil in what is called 

 the neutral condition, because they are 

 ready to infect many different species of 

 leguminous plants indifferently. They 

 are very small, about 8// long by 0'2/t 

 broad, and are in active motion, each 

 possessing a single cilium. Because of 

 this activity they are sometimes said to 

 be in the " swarm " stage, and in this 

 form they infect the host plant by 

 entering through the root-hairs. 



Once they have entered the root-hairs, 

 they begin to secrete slime and extend 

 into the cells of the root, near the nuclei 

 of whish they begin to multiply rapidly 

 as bacilli, rods about four times the size 

 of the bacteria tree in the soil. 



Finally, after two or three weeks, the 

 bacilli begin to form still larger entities. 



