44< ANATOMY AND PHYSIOLOGY OF 



the other colouring matters of plants. The reds and blue*^ are usually 

 dissolved in the cell-sap ; in particular the red colouring matter of leaves, 

 which acquire this colour in autumn, that of most flowers and red fruits ; 

 and in like manner the blue colouring matter of most blue j9.owers. Only 

 in very rare cases do we find the red and blue colouring matter of flower 

 in the form of globules, e. g,, the red of Salvia splendens and the blue of 

 Strelitzia, reginm. Whether the pigment is here as in chlorophyll con- 

 nected with a foreign matter forming the globules, or itself alone consti- 

 tutes these is unknown. The yellow colour of leaves which are bleached 

 in autumn consists of altered chlorophyll (Xanthophyll) ; in flowers the 

 yellow pigment usually occurs in the form of globules ; but in other caseb 

 diffused uniformly in the ceH-sap ; in the yellow perigonial^ leaves of 

 Strelitzia it has the form of slender, crescentically curved and irregularly 

 wound fibres, which swim in the cell-sap. In the red coloured Algae, the 

 chlorophyll seems, at first sight, to be replaced by red colouring matter, 

 but according to the researches of Klitzing {^^ Fhycologia genendis'' 21), 

 green chlorophyll granules are also present, only their colour is hidden by 

 the red colouring matter which accompanies them. 



Starch (Amylum) is still more widely diffused than chloro- 

 phyll, since perhaps no plants except the Fungi are without it. 

 Whether or not starch occurs in an amorphous condition is still 

 doubtfal. Sehleiden Q' Orundzuge'' L 181) believes that he found 

 it in this state in Sarsaparilla^ in the rhizome of Gareoo arena- 

 ria, and in the seeds of OardamomuTn minus. It is likewise 

 doubtful if it occurs in a state of solution, for I have repeatedly 

 seen the sap of particular cells, particularly of Zygnema, but 

 also of Phanerogamia, e. g., of the Potato, acquires a wine-red 

 colour with iodine ; but this colour is no certain sign that we 

 have to do with starch. The form in wliich starch occurs uni- 

 versally is that of small, colourless, transparent granules, which are 

 accumulated in the cells without definite arrangement and in 

 variable number, sometimes swimming jfreely in the sap, some- 

 times slightly adherent to the wall. Their size varies from 

 an immeasurably small diameter to a magnitude visible even to 

 the naked eye (according to Pay en fi*om 2-lOOOths of a milli- 

 metre in Ghenopodium Quinoa, to 185-lOOOths in the Potato) ; 

 granules of very different diameter occur together in the same cell, 

 out the maximum size of the granules of each plant is tolerably 

 definite. 



Like the size, the form of the granules varies extremely in dif- 

 ferent plants, and is sometimes so characteristic, that in many 

 instances we can determine with tolerable certainly, by the micro- 

 scope, the source where a starch has been obtained. Small gra- 

 nules are mostly regularly globular ; but the larger full-grown 

 granules exhibit very irregular forms in many plants, being 

 sometimes elongated into the shape of rods, sometimes flattened, 

 sometimes made to assume angular form by mutual pressure, 

 and mostly possessing irregular projections. (See the figures 



