1 70 On the Selecting Power of Plants 



only 16 grains of the dried barley straw, and being burnt, left 

 no more than 1 grain of ashes, — a quantity so much less than 

 what would have proceeded from the 100 grains of barley, of 

 which it was the produce, that I thought it useless to carry the 

 examination of them any further *. 



I may remark, that all the four samples of barley-straw, which 

 had been watered with the strontian solution, were examined 

 with care, in the hope of detecting in them the presence of that 

 earth ; but the earthy matter obtained from those planted in 

 sea-sand and in sulphur presented not even a trace of it, that 

 from sulphate of strontian only 0.3 of a grain, that from Carrara 

 marble only 0.4, — an amount beyond comparison smaller than 

 what would have been present had it been secreted with the 

 same readiness as a calcareous salt would have been. Yet that 

 the presence of nitrate of strontian did in some measure contri- 

 bute to the growth of the plant, may be inferred by comparing 

 the amount of barley-straw obtained from the flowers of sulphur 

 watered with that solution, and that from the same matrix 

 moistened merely with distilled water. In the first case, the 

 barley-straw weighed 78 grains, and the ashes derived from it 

 7 ; whilst in the second, that from an equal amount would have 

 yielded 48 grains, and its ashes only 3 grains. The same year 

 a similar train of experiment was pursued with the Lotus tetra- 

 gonolobus, or winged pea trefoil. Six hundred grains of the 

 seeds of this plant were sown in each of the boxes employed in 

 the foregoing experiments. They were moistened from time to 

 time, as before, with water containing two ounces of nitrate of 



* M. Laissaigne, as quoted by M. Richard, made an experiment to the 

 same effect, and with similar results to this of mine. But his mode of con- 

 ducting it appears in this respect unsatisfactory, inasmuch as the plant was 

 taken up before it could be expected, in the natural course of things, to have 

 begun to draw upon external sources for a supply of earthy matter. It is 

 well known that the albumen of the seed is expressly provided for the nutri- 

 ment of the infant plant ; hence, the first effort of germination is to produce 

 nothing more than an evolution of matter previously existing in the seed, 

 and it is only in the future progress of the plant towards maturity, after this 

 internal supply has been exhausted, that we can hope to trace, if at all, any 

 increase of earthy or alkaline matter. Now M. Lassaigne's experiment was 

 stopped at the end of fifteen days, a period too short to admit of much acces- 

 sion of earthy matter from without to have taken place — See Richard's Ele- 

 ments of Botany, English Translation by Dr Clinton, p. 213. 



