394 Vegetable Phijsiulorju. 



coalesce into one mass, which contracts (apparently with the 

 primordial utricle separated from the cell-wall closely investing- 

 it) and forms a fmely-granular heap in the middle of the cell 

 (fig. 9, e) ; this mass commonly exhibits a rather large central 

 cavity filled Avith colourless liquid. The granular mass retains 

 its bright green colour for several days ; its granular appearance 

 is chiefly dependent on exceedingly fine green points, probably 

 minute globules of the green fatty colouring matter. The granu- 

 lar substance, with the green colour equably diffused, greatly 

 resembles the green cell-contents of some microscopic Alga^, such 

 as Protococcus. 



When the cells are soaked in strong acetic acid, the form of 

 the chlorophyll-granules is quickly lost, and they, together with 

 all the rest of the cell-contents, coalesce into an olive-coloured 

 liquid (?) substance, filling the entire cavity of the cell. In 

 iriany cases this liquid exhibits numerous blackish molecules, 

 probably separated globules of fatty substance (fig. 9,y). 



The anatomical conditions, together with the reactions just 

 detailed, which on the whole are the same as those exhibited by 

 the colourless protoplasmic cell-contents of other cells, — making 

 exclusion of the green substance soluble in alcohol, — lead to the 

 cone lusion that what is commonly described as chlorophyll is a 

 st)mewhat complex and, to a certain extent, variable matter. It 

 appears legitimate to assert that the basis of chlorophyll-granules, 

 Ijands, &c., is formed by protoplasmic (albuminous) substances 

 organized into definite forms, and in such a state of chemical 

 composition that the action of light causes the formation, within 

 their mass, but from without inwards, of a fatty matter associated 

 Avith a green colouring principle. The fatty matter must exist in 

 an intimately divided condition, and its presence in a kind of 

 suspension probably causes the greater resistance of the outer 

 than the inner part of the granules to the action of water, causing 

 their expansion, vacuolation, and even bursting by endosmose of 

 water. In a few cases the green-coloured fatty substance is 

 developed at once in the ordinary protoplasm of the cell, in 

 masses and streaks, or diffused uniformly throughout a granular 

 mass filling the cells. 



The green colouring principle may be separated from the fatty 

 substance ; it is present only in extremely small quantity, and its 

 analysis shows that it contains nitrogen, which is absent from the 

 fatty basis. Its origin and characters are still involved in great 

 obscurity. This green matter of chlorof)hyll is closely connected 

 with the colouring matters of autumn leaves, red cabbage, beet, 

 &c., but this subject will be best dealt with separately hereafter. 



The above-described conditions of chlorophyll present features 

 of still greater interest when we consider them in connexion 



