PHYSIOLOGICAL BOTANY. 213 



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 surrounding 

 membrane ; we have never seen it. Although we may 

 find granules, and subsequently cells, in a clear liquid, it 

 does not follow that the former are formed from the latter, 

 moreover, the young cells under these circumstances are 

 frequently empty ; sometimes certainly they contain several 

 nuclei. Moreover, it is hypothetical and cannot be seen, 

 that the nucleus of the cell converts part of the liquid 

 into 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 wall 

 becomes converted into cellular matter, and that in this 

 manner the cells are perfected. It is by no means my 

 intention to assert, that these facts are false; I merely wish 

 to say, that we must not commence with these statements 

 with what is doubtful and uncertain. 



I have several times reminded the reader that the cells 

 of the Alga3 cannot be regarded as analogues by which 

 the development of cells in the Phanerogainia can be 

 explained. The cells of the Algae are rather to be com- 

 pared to the joints of the stem in the Phanerogamia, than 

 with the individual cells of which the stem is composed. 

 The cells of the Algae are placed in a long tube, and 

 hence were called utriculi, and, in fact, utriculi matricales 

 by Roth. Moreover, the remarkable phenomena which 

 are perceptible in several of the cells of the Algae, as, 

 e. g. in Spirogyra, Stellulina, &c., appear to characterise 

 them as peculiar organs. The author remarks, in passing 

 (p. 205) : " To guard against false views I must observe 

 here, that the theory of crystallization brought forward 

 by Link, according to which crystals are formed by the 

 confluence of small globules, depends upon imperfect 

 observation." I never thought of saying anything of the 

 kind. When a recent precipitate, as e. g. of carbonate of 

 lime, is quickly placed under the microscope, we observe 



