290 



ASSIMILATION. 



for instance a leaf of Vallisneria or of Anacharis, is treated 

 with a solution of one part of concentrated hydrochloric acid 

 in four parts of water, the first change observed is merety a 

 fading of the green color of the granules to a yellowish or 

 brown. After a few hours, however, upon the periphery of each 

 granule there appears a small rounded mass of a deep brown 

 color, generally keeping much the shape of the granule from 

 which it has been extruded. Often more than one of these 

 masses can be detected, and they sometimes assume needle-like 

 or staff-like shapes. But, whatever their form may be, they 

 carry out of the granule all of the coloring-matter, and leave it 

 as a honey-combed mass of its original shape. Similar extrusion 

 of a colored mass can be effected b}' the action of the vapor of 

 boiling water, or even by immersion in boiling water ; bul here 

 the change is produced in a single hour, or even less (in some 

 cases, in five minutes). When much starch is present in the 

 chlorophyll granules there is general!}' considerable change of 

 outline of the whole mass, and more or less breaking down of 

 their internal structure. The nature of the vehicle which, under 

 the action of hydrochloric acid or moist heat, carries out of the 

 granule all of the coloring-matter, will be referred to later, under 

 the name given it by Pringsheim, namely, Hypochlorin. 



773. The mass of the granule is left by this removal of its 

 coloring-matter, as a spongy body of about the original shape 

 of the granule. This spongy stroma, or " trabecular mass," is 

 plainly different from the granule which is decolorized by the 

 action of solvents, for example, alcohol, ether, etc. ; for in the 

 latter case the mass appears to be with an unbroken contour, 

 and has a solid structure. 



774. The chlorophyll pigment can be extracted, although with 

 various associated waxy and fatty matters, by alcohol and other 

 solvents. To prepare a solution of the pigment for a study of 

 its most striking properties, fresh leaves should be bruised, acted 

 on for a few hours in the dark by warm, strong alcohol, and 

 then, without exposure to bright light, the liquid should be 

 carefully decanted. It is not difficult to separate the dark 

 green solution into two distinct colors by means of the following 

 methods : 



(1) Fremy's process. One volume of the alcoholic solution 

 is shaken with a mixture of two volumes of ether and one of 

 concentrated hydrochloric acid ; after standing for a time, its 

 upper, or ether layer, is yellow (phylloxanthin or xanthophyll), 

 while its lower, or acid layer, is blue or greenish blue (phyllo- 



