DISCOURSE OF W. B. TAYLOR. 337 



of organic matter contained in the latter, is but a fraction of that 

 which was originally contained in the former. We can account in 

 this way for the disappearance of a part of the contents of the sac, 

 which has evidently formed the pabulum of the young plant. But 

 here we may stop to ask another question : By what power was the 

 young plant built up of the molecules of starch? The answer 

 would probably be, by the exertion of the vital force : but we have 

 endeavored to show that vitality is a directing principle, and not a 

 mechanical power, the expenditure of which does work. The con- 

 clusion to which we would arrive will probably now be anticipated. 

 The portion of the organic molecules of the starch, &c. of the 

 tuber, as yet unnaccotmted for, has run down into inorganic matter, 

 or has entered again into combination with the oxygen of the air, 

 and in this running down and union with oxygen, has evolved the 

 power necessary to the organization of the new plant. - - - We 

 see from this view that the starch and nitrogenous materials in 

 which the germs of plants are imbedded, have two functions to 

 fulfill, the one to supply the pabulum of the new plant, and the 

 other to furnish the power by which the transformation is eifected, 

 the latter being as essential as the former. In the erection of a 

 house, the application of mechanical power is required as much as 

 a supply of ponderable materials." * 



The less difficult problem of the building up of the plant after 

 the consumption of the seed, under the direct action of the solar 

 rays, is then considered;, the leaves of the young plant absorbing 

 by their moisture carbonic acid from the atmosphere, which being 

 decomposed by solar actinism, yields the de-oxidized carbon to enter 



* Agricultural Report, for 1857, pp. 440-444. In May, 1842, Dr. JULIUS R. MAYER 

 published in Liebig's Annalen der Chemie etc. his first remarkable paper on 

 "The Forces of Inorganic Nature," constituting the earliest scientific enunciation 

 of the correlation of the physical forces; and (if we except the work of SEGUIN in 

 1839,) of the mechanical equivalent of heat. (Annalen u.s.w. vol. xlii. pp. 233-240.) 

 In September, 1849, Dr. R. FOWLER read a short paper before the British Asso- 

 ciation at Birmingham, on "Vitality as a Force correlated with the Physical 

 Forces." (Report Brit. Assoc. 1849, part ii. pp. 77, 78.) In June, 1850, Dr. W. B. CAR- 

 PENTER presented to the Royal Society a much fuller memoir " On the Mutual 

 Relations of the Vital and Physical Forces." (Phil. Trans. R. & vol. cxl. pp. 

 727-757.) Neither of these essays accounts for the amount of building energy dis- 

 played in the development of the seed, under conditions of low and diffused 

 heat: and the expression "Vital Force" used both by FOWLER and CARPENTER, 

 was studiously avoided by HENRY. 



22 



