PHYSIOLOGICAL BOTANY.

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Chcmie,’ 32, Bd. s. 198. He subjected Cetraria Islandicaand Agaricus albus to elementary analysis, and his resultsagree tolerably well with those of Payen. He then makesthe following remark : “ I am also satisfied as to theperfect accuracy of his experiments, yet I cannot deny thatI am astonished, first, at not finding it stated anywherethat he previously determined the amount of ash, exceptin his first memoir (Annal. des Sciences Natur., 2 ser.t. ii, p. 27), since even if he had not found any ash pre-sent, he ought to have mentioned it; moreover, sincenone of the substances mentioned by myself as havingbeen analysed were perfectly free from the so-called in-crusting matter, and since the results of Payen lead tothe same conclusion, which is explained by the intimacywith which these substances permeate the primary cellulartissue; and again, since silica, which is so generally dif-fused throughout the vegetable kingdom, would veryprobably have entered into the composition of thesematters, it does not appear possible that the vegetablestructures subjected to examination could have been per-fectly free from silica.” This suggestion is quite correct.Payen gives the amount of ash contained in the vegetablestructures when not yet separated from the matters depo-sited upon the cellulose. We thus find that 10'80 p. c. ofsilica are stated to exist in the leaves of Endive, but nonein the leaves of the same plant when exhausted of every-thing but the cellulose. This is very improbable, for theamount of silica in the leaves of the Graminacese, beforepurification, is stated to be 12'25 ; but I find no analysisgiven of the leaves after purification. But in this casethe amount of silica existing in the cellulose must be verylarge, for the incinerated leaf is so completely convertedinto silica, that all its parts can be accurately distinguishedunder the microscope; a remarkable phenomenon, andone which still requires careful investigation, because itis opposed to what we know regarding cellulose.

In the same ‘ Scheikundige Onderzoekingen,’ 1. c. p. 62,

‘ Journal f. Prakt. Cliemie,’ 1. c. p. 204, we have an

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