OCR Text |
Show 139 knowledge ot the respective functions of different cons ituents is thus far very limited. We are aware that the amount oi potassa in these plants is in a certain ratio to the bulk of fiber and the soluble carbohydrates ; we know, also, that without iron no reduction of carbonic acid and water can take place; further, that the phosphoric acid stands in close relation to the bulk of nitrogemzed matter produced, and that without sulphates in the soil there is no production of albumen, but we have as yet no insight into the nature of these relations, and no satisfactory ohemical explanation of the processes. With regard to some inorganic constituents of plants, we do not know even whether they are essential, for instance as regards magnesia and silica. The latter, as asserted by some experimenters, is entirely useless, but it must be borne in mind that the experiments upon which this assertion is founded were made with plants thriving io aqueous solutions in which all the other mineral constituents were present except silica. Whether such plants grown under such artificial circnmstances, with an abundant accession of water, wonld stand an occasional drought as well as plants grown in soil, remains to be seen. The question as to how a dry climate affects the nature and amonnt of the mineral constituents of the vegetation is interesting, but can be satisfactorily answered only after a great number of analyses. Some plants are exceedingly rich in mineral matter and dry up sometimes in the ground without losing their shape or color of leaves and flowers; the dead plants crumble to powder between the fingers, while from the intensity of the color of their flowers they appear as though in a living condition ; Zinnia anomala- a fine yellow composite- may De mentioned. The same species of plant very often shows considerable difference in the composition of the ashes, according to the soil in which it was grown; therefore much precaution should be had in forming conclusions. In the following table are the analyses of three German and two New Mexican grasses, from which it will be seen that great differences exist between the two classes as regards their composition. Potassa., Soda. Lime Magnesia Oxide of iron.... Phosphoric acid Sulphuric acid... Silica Chlorine a 4i Total. 7.63 2.01 0.98 1.50 0.16 80.61 0.10 8.53 Trace 8.57 3.04 0.41 3.01 0.81 76.81 Traces 99.60 I 100.18 9.33 0.31 6.35 1.31 0.23 2.15 3.99 77.27 0.33 100.16 43.3 3.9 1.3 0.5 6.3 8.2 39.0 4.5 38. 45 0.69 5.65 3.72 0.28 10.60 4.28 13.08 6.64 101. 0 102.39 No. 1.- Ashes of Bouteloua fcena, )\ , N ew Mexico. No. 2.- Ashes of Bouteloua hirsuta, ) No. 3.- Ashes of Arnudo phragmites, ) No. 4.- Ashes of Alopecurus praterwis, > Germany. No. 5.- Ashes of Poa pratensis, ) Respectfully submitted. Lieut. GEO. M. WHEELER, Carps of Engineers. O. LOEW, Jdineralogical Assistant. APPENDIX 11. ZOOLOGICAL REPORT, FIELD- SEASON OF 1874. I. General Itinerary, by Acting Assistant Surgeon H. C. Yarrow, United States Army. II. Notes, by H. W. Henshaw, ornithologist. III. Notes, by O. £ . Aiken, assistant. I . GENERAL ITINERARY, BY ACTING ASSISTANT 8URGEON H. C. YARROW, UNITED STATES ARMY. UNITED STATES ENGINEER OFFICE, GEOGRAPHICAL EXPLORATIONS AND SURVEYS WEST OF THE ONE HUNDREDTH MERIDIAN, Washington, D. ft, June 30,1875. SIR : In accordance with verbal instructions, I have the honor to submit the following report upon the operations and investigations in the zoological and botanical branch of the survey during the past year. |