262 



KNOWLEDGE. 



[NOVEMBEE 1, 1895. 



gatious entered into with the view of elucidating this led to 

 the following results, the value of which cannot be over- 

 estimated, viz., " that when cereals and leguminous plants 

 were grown in a sandy soil to which the requisite mineral 

 manures were added, and the nitrogenous matter given in 

 the form of nitrate, the cereals made growth and attained 

 vigour in direct .proportion to the amount of nitrate given 

 to them, when the amount provided was small ; so that a 

 double dose of nitrate caused the growth of a two-fold 

 amount of organic matter, a treble dose gave a three-fold 

 increase, and so on until the amount of nitrate had been 

 added which enabled the plants to grow to their normal size, 

 when, of course, the further addition of nitrogen had less 

 and less efl'ect upon the amount of organic matter produced. 

 The cereals were able to assimilate the nitrate directhj, and 

 their growth in a soil otherwise fertile depended precisely 

 upon the amount of nitrate present. With the leguminous 

 plants no such correspondence was observed. Their growth 

 was quite capricious, and, indeed, sometimes the soil CDn- 

 tainnig the least amount of nitrate produced the largest 

 and healthiest plants. It seemed from many experiments 

 that leguminous plants — such as peas, clover, and lupines — 

 were very little dependent on the nitric acid {i.e., the 

 nitrate) of the soil for their nitrogenous nourishment." 



It followed from this that the source of nitrogen for 

 leguminous plants, at all events, must be atmospheric 

 nitrogen, either combined or free ; and — not to weary the 

 reader with too many details — it was conclusively estab- 

 lished by the experimenters just named that the free 

 nitrogen of the air constituted this source. It was further 

 found that the ability of the above order of plants to 

 assimilate free nitrogen was associated in some way with 

 the tubercles in their roots. " Lupines which were grown 

 in sterilized soil, but provided with all the elements of 

 fertility, might grow well enough, but the crop produced 

 contained no more nitrogen than had been provided in the 

 soil and in the seed, and their roots contained no tubercles. 

 On the other hand, when grown in a soil containing very 

 little nitrogen, but in which the micro-organisms associated 

 with the growth of tubercles were present, it was noticed 

 that the plants grew to a certain stature and then began 

 to droop. Cereals grown under similar conditions presented 

 a simUar appearance, and eventually died down ; but in the 

 case of the lupines, after passing through the drooping stage 

 and losing some of their leaves, they revived, shot out new 

 leaves, and grew at length to full stature. AVhen the crop 

 was analyzed, and also the soil in which it was grown, it was 

 found that there iras a notable increase of nitroijen in both " 

 (the italics are ours). "This is precisely what Georges 

 Ville found in his experiments thirty years before, and 

 which he described to an incredulous world, and the con- 

 clusion he arrived at was the same, viz., that leguminous 

 plants are able to utilize the free nitrogen of the air in 

 building up their tissues." (Of course Ville had not at 

 that time any idea of the agency of micro-organisms 

 here.) The accuracy of Hellriegel and Wilfarth's results 

 has since been thoroughly verified, the assimilation 

 of nitrogen by leguminous plants and the growth of the 

 tubercles having been made the subjects of prolonged study 

 and observation. Much, however, still remains to be found 

 out in regard to this, for, as Dr. Aitken says, while the 

 fact that leguminous plants do assimilate free nitrogen 

 seems to be abundantly proved, the place where tbe 

 assimilation occurs and the conditions under which it 

 occuL's are still matters of conjecture. 



Berthelot has shown further that — altogether apart from 

 the growth of leguminous plants — some soils are capable 

 of absorbing the free nitrogen of the air, this being due to 

 the presence of small unicellular alg%. Liter researches 



of Kossowitch, on the other hand, appear to show that 

 algie have only an indirect, but none the less important, 

 influence upon the process. Prof. Frank, of P)erlin, 

 after long study of the subject, has been led to the 

 conclusion that the tubercles on the roots of leguminous 

 plants are not tbe cause of their ability to absorb free 

 nitrogen, but they are rather the result of that process. 

 He is also of opinion that the seat of the assimilation of 

 free nitrogen is to be found in the chlorophyll cells, where 

 it was long ago proved that the decomposition of carbonic 

 acid by plants and the fixation of its carbon takes place. 



" He (Prof. Frank) makes no difference between 

 leguminous plants and others as regards their abdity to 

 assimilate free nitrogen in their chlorophyll cells, whde 

 he acknowledges that that order of plants possesses the 

 power in a very remarkable degree. He is, therefore, of 

 opinion that wiiile fallow land, poor in organic matter, 

 may become richer in nitrogen through the growth and 

 nitrogen assimilation of minute cryptogams therein, that 

 enrichment is greatly augmented when plants of a higher 

 order are grown upon the land." 



From what has been said it will be seen that the whole 

 question of the assimilation of free nitrogen is in a most 

 interesting stage. P>iit the actual and hard-won experi- 

 mental proof of the fact that the free nitrogen of the air, 

 as such, can be taken up and is taken up by certain kind.s 

 of plants, assuredly marks an epoch in the history of 

 agricultural science. Readers who desire to enter into 

 the subject more fully should refer to Dr. Aitken's able 

 paper, for which the thanks of all who are interested in 

 scientific agriculture, but who are precluded through want 

 of time or otherwise from entering minutely into such 

 points themselves, are due. 



Some 3Clc(cnt patrnts, 



C. aud P. Pollock. Connecticut, U.S.A., A. JI. Monvll and T. L. 

 Murphy, Now York. U.S.A. Devices for spraying water or other 

 fluids. Tliis invention relates to devices for spraying water or other 

 fluids, for extinguisliing fires. oi' for use on gardens, lawns, &c., and 

 consists of a tube having a bell-shaped flaring mouth, wiihin which is 

 a ball of euch size as to fill the bell-mouth. A guard, passing across 

 the mouth of the bell, but at such a distance from the ball as to allow 

 the latter considerable freedom of movement, serves to hold the ball 

 in place when the sprinkling device is not in use. This guard, however, 

 has no function while tlie spriokling device is in use and water is 

 flowing through it, f )r the action of the water in passing around the 

 ball is such as to hold the ball firmly in the bottom of the bell-mouth 



preventing it from escaping, and this independently of the water 

 pressure. The water in passing around the ball is turned into 

 spray, which forms in tlrops so large thnt they are not readdy 

 blown away by the wind, nor instantly dissipated by the heat of a 

 fire. The figures show an elevation and section, as constructed 

 for firemen's use, and provided with a straight-stream discharge 

 tip 7, and a spray tip 8. The plug 3 is cut away so as to form a port 

 or passage by which the water may be directed through the straight, 

 stream port 5 or the sprav port 6. 



A'o. 11,148, Dated 6d Jung, 1S96. Aocejpted 17 1 A August, 1S95. 

 Twelve figures. 



