342 



PROCEF.niN(JS OF TIIK 



titv i)t' nini^nosia in tlu* soil, and in so tar a p;roal dilVcronce bo- 

 twoen it and tlio scrpontino, .still 1 cainiot say that it is wholly dcs- 

 tiiute of it. In '.HK)() grains of soil I found six grains of rnai;nesia j 

 this is about one.third jjart j)er cent, or at the rate of M) per 

 1(),(MM), a very small (|uantity no doubt when conijjared with the 

 Serpentine whiih contains it at the rate of about i)arts in 



lO.OOO, and whiih niiijht therefore be expected to yield a soil 

 containing- a very considerable proportion of the earth ; it must, 

 howcN cr, be renieiubered that s>n h a (piantity of niaf;nesia as I 

 have mentioned is very considerable when comi)are(l with what 

 plants rc(juire, and the (piantity which any crop removes ; amount- 

 ing;- in fact to many thousand pounds weight per acre on the very 

 lowest computation. 



The greatest quantity of inou(;anic mattkrs is absorbed by 

 plants in the earliest stji^es of their growth, that is to say, 

 when examined, youn^ i)lants are found to contain in proj)ortion 

 far more earthy and saline substances, than similar j)lants of more 

 advanced aa;e. In order to trace, if possible, the stage at which 

 this inlluence commences, a series of experiments was made on 

 the etfects of sdine and other substances on the germination of 

 seeds. The result obtained was unexpected, because as, in the 

 commencement of germination, the first clfcct is usually a mere 

 softening or swelling up of the whole mass, and therefore 

 rather a mechanical etfect, it was not expected that this part 

 of the process could be affected by small quantities of saline 

 matters. It appeared however that the swelling of the seeds 

 and consequent germination was influenced by the presence of 

 certain substances. Weighed portions of seeds, principally the 

 common Windsor bean, were immersed in weak saline solutions, 

 and weighed after a certain period, which of course shewed the 

 increase they had gained by immersion in the various fluids. It 

 is generally stated that seeds germinate better or more rapidly in 

 the dark than when exposed to the influence of light. It would 

 appear however that this is not always the case, for in some 

 solutions the seeds exposed to lia:ht, germinated most rapidly. 

 No saline substance that was tried caused the seeds to germinate 

 more rapidly than they did under ordinary conditions in pure 

 •water, but many saline substances caused them to germinate far 

 more slowly in darkness than in light. To refer at once to an 

 experiment. It was found that — 



Beans weighing 1000 became in light 1309, in darkness 1362, 

 when immersed in pure water. 



But the same weight became in light 1282, in darkness 1066, 

 in very dilute muriatic acid. 



I mention this as a strong case, for in light the presence of 



