260 Dr. Daubeny on the Degree of Selection exercised by Plants, with regard 



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 OS of a grain, that from Carrara 

 marble only 04, — 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 contribute 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 

 tetragonolohus, 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 strontian to the 

 ten o-allons, and they were not cut down until the whole of this water had 

 been expended upon them. 



In order the better to arrive at an approximation to the actual increase of 

 solid matter obtained during the process of their vegetation, the plants were 

 taken up by their roots, and the adhering earthy matter carefully detached ; 

 but lest this should have been incompletely effected, the stems and other parts 



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 nutriment of the infant plant ; hence, the first effort of germina- 

 tion 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. Laissaigne's 

 experiment was stopped at the end of fifteen days, a period too short to allow of much accession of 

 earthy matter from without to have taken place. — See Richard's Elements of Botany, English Trans- 

 lation by Dr. CUnton, p. 213. 



