t 413 ] 



LIII. Further Observations on the Structure of the Solid Ma- 

 terials found in the Ashes of recent and Fossil Plants, By 

 the Rev. J. B. Reade, M.J* 



TN every inquiry connected with the physiology of plants, it 

 will be necessary to bear in mind that " the chief end and 

 object of the various processes into which the function of 

 nutrition may be divided, is the manufacture of the materials 

 which are ultimately to be assimilated into the vegetable struc- 

 ture, and by which it is to be nourished and developed in all 

 its partsf." In the practical application of this important 

 principle all writers on physiological botany, whether in En- 

 gland or on the Continent, have adopted the opinion that 

 carbon alone, fixed under the form of a nutritive material, is 

 elaborated for the development of all parts of vegetable struc- 

 ture. " The solid materials," says M. Biot, " the fixation of 



which constitutes the skeleton of the plant may be known 



by the analysis of the dead or withered vegetable, but even 

 among these we have to distinguish those which are essential 

 to the existence of the plant and those which have been acci- 

 dentally raised from the earth by the roots with the water in 

 which they were dissolved." " I shall be careful, therefore," 

 continues M. Biot in his Analysis of the Vegetation of the 

 Graminece J, "not to commit myself in these complex ques- 

 tions, for which all the assistance of chemistry and of the mi- 

 croscope is scarcely sufficient. I shall confine my remarks to 

 a few of the alimentary products of plants which are known to 

 be composed by them, and conveyed into their various parts, 

 whilst undergoing the metamorphosis produced by vitality." 



Among the solid materials represented by M. Biot as ac- 

 cidentally taken up, Professor Lindley ranks earths, salts, and 

 metals. In fact, he considers all principles which cannot be 

 referred to either hydrogen, oxygen, carbon, or azote to be 

 foreign to plants. (Introduction to Botany, book ii. chap. 3.) 

 " There are, however, some experiments," he adds, " which, 

 if they could be depended on, would materially weaken these 

 hypotheses. Schrader grew barley and rye in well washed 

 flower of sulphur moistened with distilled water: they were 

 afterwards analysed, and found to contain silex, lime, and 

 magnesia as well as oxides of iron and manganese. The same 

 plants produced in earth did not yield a greater weight of 

 ashes than those grown in sulphur; and these experiments 

 are confirmed by those of Braconnot as recorded in the Jn- 



* Communicated by the Author ; whose former paper on the same sub- 

 ject will be found at p. 13 of the present volume. 



f Cabinet Cyclopaedia. Henslow's Principles of Botany, p. 227. 

 \ Scientific Memoirs, vol. i. p. 585. 



