and the Function of Chlorophyll in Plants. 71 



The universality of the occurrence of this body in all green 

 chlorophyll-bearing plant-cells, its generation in light, its 

 relation to oxygen, and its behaviour to the amylaceous con- 

 tents of chlorophyll-bodies scarcely permit us to doubt that it 

 is a true primary assimilation-product of green plants, from 

 which, under the influence of light, are brought forth by 

 oxidation the starch and oil enclosures of the chlorophyll- 

 bodies as the reserve-substances destined to supply the elements 

 for the circulation. 



Hypochlorin, further, proves itself to be the most readily 

 combustible, in light and oxygen, of all the constituents of 

 the cell. It is consumed even sooner than chlorophyll by 

 intense light in the presence of oxygen. For the ordinary 

 intensities of light, under which the plant vegetates, chloro- 

 phyll affords sufficient protection to hypochlorin. With the 

 heightened intensities in the experiments, that shelter no 

 longer suffices, and even the light transmitted by the 

 chlorophyll is intense enough for its rapid destruction in 

 oxygen. 



That hypochlorin, present in the normal conditions of the 

 plant in variable amount in every grain of chlorophyll, is sub- 

 jected to an uninterrupted increase and decrease can easily 

 be shown ; and all comparative investigations between younger 

 and older states of development of the chlorophyll-grains de- 

 cidedly indicate that the accumulation and growth of starch in 

 the ground-mass of chlorophyll-bodies advances hand in hand 

 with a diminution of the hypochlorin in them. In darkness 

 the hypochlorin (which, as it appears at least from my expe- 

 riments hitherto, does not directly participate in the circulation 

 of substance) is more stable than the starch — which again 

 only shows that its transformation into more highly oxidized 

 substances in the cell is accelerated by the heightened respira- 

 tion in the light. 



The facts here briefly sketched disclose a series of new 

 points of view for judging of the action of light on plants. 

 The demonstrable conditions under which the destruction of 

 chlorophyll in the living plant is effected, the knowledge of 

 the eminent augmentation of the amount of respiration with 

 the increase of light-intensity (which may in every colour 

 grow to such a degree as to destroy the cell), the undeniable 

 influence exerted by the light-absorptions in the chlorophyll 

 upon the amount of the respiration, finally the discovery of 

 hypochlorin with its properties, conditions of origin, and 

 behaviour in light, permit, if I am not mistaken, a more 

 correct estimate of the hitherto misunderstood oldest and most 



