182 UTRICULAR STRUCTURES. 



the starch-globule were only coated with colouring matter 

 (chlorophyll) . 



A fifth condition. One or more starch-globules ori- 

 ginate in the colouring matter (fig. 12, af), which in- 

 crease in size, and finally almost fill the utricle (fig. 12, 

 ff /). The colouring matter (chlorophyll) by degrees 

 vanishes, at last entirely, and finally the membrane also 

 of the utricle is dissolved, and the starch-globules lie free 

 in the cell (fig. 12, m, n}. 



These are the principal alterations which take place in 

 the contents of the colour- utricles. I have chiefly ob- 

 served them in chlorophyll -utricles. Nothing general 

 can be said respecting the distribution of the forms men- 

 tioned. As a rule, all or many are met with in the same 

 Natural Order. I have, however, met with green utricles 

 with contents remaining homogeneous, and those minute 

 starch-globules, coloured blue by iodine, much more fre- 

 quently in the Algae and Mosses ; those with large starch- 

 globules, coloured blue by iodine, more frequently in the 

 higher plants. The red-utricles of the Florideae gene- 

 rally exhibit only homogeneous red contents. The yellow 

 and blue utricles I am not yet sufficiently acquainted 

 with. 



It still remains to be noticed that globules occur, in 

 rare instances, in the place of the starch, inside the colour- 

 utricles, which are either not coloured at all by iodine, or 

 become yellow. In my opinion they are corn-posed of 

 a substance analogous to starch ; allied to gelatine and 

 inuline. But I cannot agree with Schleiden, who says, 

 that chlorophyll (the chlorophyll-globules) often invests 

 starch, and also often other substances.* Beyond starch 

 (as ordinarily), and the globules just mentioned (which 

 occur exceptionally), I have never yet met with any 

 known solid product in the chlorophyll-utricles, for in- 

 stance, not even oil- or mucilage-granules, &c. 



The homogeneous colouring matter of the colour-utri- 



* Grundzuge, 2d ed. i, p. 190. 



