Vefjetahle Plnjsiulof/y. o03 



irregular mass, which is subsequently organized into distinct gra- 

 nules. 



It is very common to find chlorophyll granules described as 

 consisting of a waxy or fatty substance, and chemists have gene- 

 rally very readily accepted this account, from the circumstance 

 that the green colouring matter of leaves, vjcc, may be extracted 

 by alcohol, and the substance thus obtained is of the nature 

 just described. But this alcoholic extract yields a substance 

 %vhich is itself a compound, since a colourless waxy substance 

 may be obtained from it, separately from the true colouring 

 matter, which exists in very minute quantity. Not only is this 

 green waxy matter a compound substance, but, what is of still 

 more importance, it constitutes but a part of the constituents 

 of the chlorophyll granules. When the green colour is ex- 

 tracted from chlorophyll, in situ, by the action of alcohol, 

 under the microscope we find the granules left behind in their 

 original position, only colourless (fig. 9, c). The green colour- 

 ing matter may be observed at the same time upon the slider, 

 at the evaporating edges of the alcohol, deposited in fat-like 

 globules of very irregular size, some large from confluence while 

 in solution. 



A deeper investigation into the behaviour of the chlorophyll 

 granules leads to a still more decisive refutation of the assump- 

 tion that the chlorophvll granules are masses of coloured wax. 

 When we open the cavities of cells so as to allow the escape of 

 chlorophvll granules into the water, under the microscope, we 

 find them swell by absorption of water, and a kind of endosmotic 

 action is set up, bubble-like spaces often becoming hollowed in 

 the interior (fig, 17, b), into which the water penetrates and 

 " blows out " the granules. The edges of these swollen granules 

 are found to be finely granular or minutely ragged. The bubble- 

 formation through absorption of water is seen still more clearly 

 in the green bands of Spirogyra above referred to, where it also 

 reveals that the green colour resides only in the outer part ol a 

 colourless band of viscid substance, which is coagulated and con- 

 tracted by the application of alcohol or most acids (fig. 10, B). 

 When alcohol is applied to cells containing chlorophyll granules, 

 for instance those of the grasses, the granules when decolorized 

 mostly swell up at first, and subsequently become solidified, 

 seemingly by coagulation. Tincture of iodine applied to the 

 decolorized granules colours them deep brownish-yellow, the 

 same colour which it imparts to the primordial utricle, the nucleus, 

 and protoplasmic matters generally (fig. 9, d). 



When the chlorophyll-bearing cells (for instance of a barley- 

 leaf) filled with granules are digested in solution of caustic 

 potash, the granules are at first swollen, then they gradually 



