PHYSIOLOGICAL BOTANY'.

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are formed.” This is so certain, that the author com-mences with “ It appears.” It is moreover uncertain,and is doubted by many, myself among the number,whether a cytoblast is formed before the surroundingmembrane ; we have never seen it. Although we mayfind granules, and subsequently cells, in a clear liquid, itdoes not follow that the former are formed from the latter,moreover, the young cells under these circumstances arefrequently empty ; sometimes certainly they contain severalnuclei. Moreover, it is hypothetical and cannot be seen,that the nucleus of the cell converts part of the liquidinto gelatine ; that the external liquid permeates the gela-tinous vesicle and distends it, is also hypothetical; and,lastly, it is no less hypothetical that the gelatine of the wallbecomes converted into cellular matter, and that in thismanner the cells are perfected. It is by no means myintention to assert, that these facts are false; I merely wishto say, that we must not commence with these statements—with what is doubtful and uncertain.

I have several times reminded the reader that the cellsof the Algae cannot be regarded as analogues by whichthe development of cells in the Phanerogamia can beexplained. The cells of the Algae are rather to be com-pared to the joints of the stem in the Phanerogamia, thanwith the individual cells of which the stem is composed.The cells of the Alga : are placed in a long tube, andhence were called utriculi, and, in fact, utriculi matricalesby Roth. Moreover, the remarkable phenomena whichare perceptible in several of the cells of the Algae , as,e. g. in Spirogyra, Stellulina, &c., appear to characterisethem as peculiar organs. The author remarks, in passing(p. 205) : “ To guard against false views I must observehere, that the theory of crystallization brought forwardby Link, according to which crystals are formed by theconfluence of small globules, depends upon imperfectobservation.” I never thought of saying anything of thekind. When a recent precipitate, as e. g. of carbonate oflime, is quickly placed under the microscope, we observe