228 PHYSIOLOGICAL BOTANY. 



Chlorophyll) in their Ptychodal cavity, and starch." Then 

 follow observations in which, as regards the contents of 

 the cells, so far as my own investigations enable me to 

 judge, many of the details are minute and correct. In 

 fact, too minute, for these contents hardly appear to me 

 to deserve the name of cells ; the most we could call 

 them would be cell-nuclei, cell-vesicles, or, with the 

 author, nuclear corpuscles. They are always of very 

 different sizes and shapes, never equilateral, even when 

 closely crowded, hence they are not formed by internal 

 expansion ; they are never distributed regularly, and often 

 appear to be perfectly solid internally, like granules of 

 starch. The secondary cells 3 as I have denominated them 

 above, are the most regular ; they also contain small cel- 

 lular granules. The granules of Chlorophyll in succulent 

 and water-plants are of a tolerably regular figure, but 

 they appear solid, and altogether of a very different- 

 nature from the cells which surround them externally. 

 The cytoblast appears to me to be a granular mass, which 

 is possibly inclosed by a membrane, but this I will not 

 decide ; according to the author, it is a perfectly-developed 

 and not a young cell. He makes the following remarks 

 upon it : " There can scarcely be any doubt that the cell- 

 germ of the cytoblast and of the nuclear corpuscles may, 

 like that of the cavity of the Ptychode, become free and 

 capable of further development ; but it is equally as cer- 

 tain that the cell-germ does not originate exclusively from 

 this source, because it is also formed in exactly the same 

 manner as within the cytoblast, in other parts of the 

 cavity of the Ptychode of the cell, where there are no 

 cytoblasts. In fact, I believe that, as a rule, the cyto- 

 blast does not produce any propagating cells, but that its 

 function is rather the elaboration and conversion of the 

 sap of the cell into that of the Ptychode." If the 

 author believes the latter to be true, he should not say 

 that the former can scarcely be doubted. On the con- 

 trary, it is very doubtful, and has not been proved to 

 occur by any of his observations. In all these investi- 



