Contributions in geographical exploration . d that in the ash at Kodiak the amount of available (i. e., water soluble)potash was only , which is exactly the amount given by Hilgard as theminimum concentration requisite for plant growth. Phosphoric acid was presentin an even smaller amount, which Professor Foulk described as slightly more thana trace, although it was so small that he made no attempt to give it a numericalvalue. The high salt content found by Shipley is probably made up, theiefore,of salts not important to the growth of the plant. April, 1919] Be<ii)inings of Revegetatio
Contributions in geographical exploration . d that in the ash at Kodiak the amount of available (i. e., water soluble)potash was only , which is exactly the amount given by Hilgard as theminimum concentration requisite for plant growth. Phosphoric acid was presentin an even smaller amount, which Professor Foulk described as slightly more thana trace, although it was so small that he made no attempt to give it a numericalvalue. The high salt content found by Shipley is probably made up, theiefore,of salts not important to the growth of the plant. April, 1919] Be<ii)inings of Revegetation 333 nuilcli, prevents evaporation. It has not proved practicableas yet to submit this hypothesis to experimental test, but ithas been found that it is impossible to obtain in pot culturesfrom small quantities of ash anything like such vigorous growthas occurs even in dry places in the field where the plants haveunlimited possibilities of root extension with the consequentability to draw upon wide areas for the necessary quantity Photograph by Robert F. Griggs SEEDS COMING UP WHERE COVERED UP BY THE OUTWASH OF A TEMPORARY STREAM. General surface of the ash liare. Lower Katmai Valley SEEDLINGS IN DRV WA ri:R-LAIl) DEPOSITS. The distribution of only a portion of the new plants , be accounted for on this hypothesis. Those comingup in outwash deposits are often so situated as to be keptbetter drained than the surrounding level. (Sec cut above.)At first I was inclined to .suppose that such deposits were suffi-ciently contaminated by admixture of the original humus soilwashed off the mountains along with the ash to present quitedifferent and altogether more favorable conditions for the 334 The Ohio Journal of Science [Vol. XIX, No. 6, plants than the undisturbed ash deposits. But further studyled me to doubt the correctness of this view, and this doubt wasconfirmed when it was found that pot cultures of this materialwere no more successful than those in which th
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