72 



SOME CONTRIBTITIONS TO PL4WT-CHEMISTET. 



9. Nasturtium officinale. I have not been able to find any analysis 

 of the common Watercress. The following data are by no means com- 

 plete, but they afford fresh evidence of the excessive absorption and 

 assimilation of mineral matter by aquatic and moisture-loving plants. 

 The large amount of ash left on incinerating murine Alga, various 

 species of Equisetum, and even the ordinary com and root crops of the 

 farm in wet seasons, admits of easy explanation : it is interesting to 

 find the Watercress no exception to the rule. Now that it has been 

 proved that the characteristic essential oil of Watercress is not a 

 sulphuretted compound, though it is rich in nitrogen, it is not sur- 

 prising to find that this plant, in its fresh condition, contains no more 

 than "082 per cent, of sulphur, an amount which corresponds to 

 1'195 per cent, in the dry matter of the Watercress. When the 

 albuminoid matter in this plant is estimated by the carbolic pro- 

 cess (see paragraph 7 above), the analysis of fresh Watercress 

 stands thus : 



10000 



10. Fagiis sylvatica. On the 9th of May, 1875, I collected a 

 large quantity of the brown scales (perula?) from the leaf-buds of the 

 common Beech. The trees were growing on an oolitic soil, and it is 

 right to mention that a part (though I believe but a small one) of the 

 lime found in their ashes might be due to traces of adherent calcareous 

 dust. 



My object in examining these scales was to ascertain how far the 

 more valuable elements of nutrition — phosphorus, nitrogen, and 

 potassium — were thrown off by this tree in the form of these 

 protective coverings of its buds. The fallen leaf-scales were 

 found to contain 15-36 per cent, of moisture, while on incinera- 

 tion of the perfectly dry substance 7*70 per cent, of ash was 

 left ; the carbonaceous matters thus burnt off contained 0-59 of 

 nitrogen. The ash was further analysed, and was found to contain, in 

 100 parts: 



A better idea of the chemical character of these Beech-scales may 

 be formed by recalculating the above results into a difi'erent form. If 



