286 DR. M. J. SCHLEIDEN ON PHYTOGENESIS. 



men of some plants, and fi-equently in the cells of the leaf as 

 containers of the chlorophylle. It is chiefly distinguished by 

 its occurrence in all kinds of granular forms without any inte- 

 rior structure, and from its being coloured by tincture of iodine, 

 brownish-yeUow, or brown. This substance, which I shall call 

 mucus, is probably identical with that of which the cytoblast 

 consists, and with the small granules in gum which I shall pre- 

 sently mention ; the first conjecture Meyen [Vegetable Physio- 

 logy, vol. i. p. 208) has noticed as being very probable. 



Now when the starch is to be employed in new formations, it 

 dissolves, in a manner as yet totally unknown to chemistry, into 

 sugar or into gum, the latter appearing at times to pass into the 

 former, or vice versa. The sugar appears in the form of a per- 

 fectly transparent fluid, almost as clear as water, is not rendered 

 turbid by alcohol, and takes from the tincture of iodine only a 

 colour in proportion to the strength or weakness of the solution 

 of the agent. 



The gum appears as a somewhat yellow, more consistent, less 

 transparent fluid, which is coagulated granularly by the tinc- 

 ture of iodine Avith a pale yellow permanent colour. 



In the further progress of organization, in which the gum 

 is alwaj's the last immediately precedent fluid, a quantity of 

 exceedingly minute granules appear in it, most of Avhich, on 

 account of their minuteness, appear merely as black points. 

 The fluid then seems to take from iodine a somewhat darker 

 yellow, but the granules, when their size enables their colour to 

 be distinguished, seem to become by this process of a dark 

 brownish-yellow. 



This is always the mass in which organization takes place, 

 and the newly formed parts consist again principally of this se- 

 parate transparent substance, which, on being subjected to pres- 

 sure, presents to view an homogeneous colourless mass ; when 

 dried it imbibes water and swells ; it is not at all affected by 

 iodine, nor does it even imbibe it, but appears after pressure 

 colourless as before, and so completely transparent, that, if not 

 surrounded by coloured or opake bodies, it is totally invisible. 

 This substance is of frequent occurrence in plants (for in- 

 stance, in great quantity, together with a little starch, in peculiar 

 large cells in the tvibers of Orchis) ; I shall call it for shortness 

 sake vegetable gelatin, and am inclined to enumerate under this 

 head, as mere slight modifications, pectine, the basis of gum 



