PRINGSHEIM S RESEAKCHES ON CH LOROPH VLT-. 103 



In iulditioTi to all these substances the oily vehicle of the 

 chlorophyll colouring matter and the hypochlorin must be 

 reckoned as contained elements of the chlorophyll-corpuscles 

 and as normal products of their function. 



The different elements and constituents of the chloro- 

 phyll-corpuscles behave differently wiien exposed to intense 

 light. Some are affected, others are not, and it is the merit 

 of the method of investigation now being elucidated that it 

 enables a direct study to be made of the relations of these 

 constituents to respiration. 



Of the constituents just mentioned, those which are rich 

 in oxygen and occur as grains, globules, or vesicles — the 

 starch-grains, the oil-globules, the tannin-vesicles — are un- 

 affected by exposure to intense light. 



Starch grains in the chlorophyll-corpuscles have the same 

 appearance, and exhibit the same reaction with iodine, after, 

 as before insolation, and the same is true of the starch in the 

 amylum-bodies of Spirogyra. With the destruction of the 

 ciilorophyll colouring matter no formation of starch is asso- 

 ciated. If starch was present in the chlorophyll-corpuscle 

 before insolation, it is found in like amount afterwards; if 

 there was none before insolation, none is found afterwards. 

 There is neither destruction nor formation of starch as the 

 result of exposure to intense light. This is no contradiction 

 to the well-known fact of the accumulation of starch in the 

 chlorophyll-corpuscles during the day. For the explanation 

 of that is very simple. Starch is not directly formed from 

 the decomposition of carbonic acid and water; and, if in 

 liyht of no great intensity there is an accumulation of starch 

 in the chlorophyll-corpuscles, it happens because the light 

 was not sufficiently intense to destroy the formative material 

 out of which the starch is constructed. 



Oil globules, both within and outside the chlorophyll-cor- 

 puscles, behave in every respect like starch. At least all 

 the colourless and oil-like globules, such as occur in the 

 bands ^{Spirogyra, in the chlorophyll- corpuscles of Characecs, 

 Vaucheria, Fontinalis, Sec, which are to be considered as of 

 a fatty and not of a volatile oil, do. 



Tannin-vesicles of Mesocarpus are indestructible by light 

 alone. They are, as already noticed, very sensitive to hurt- 

 ful agencies^ and when the cell is killed by light they are, 

 of course, decomposed; but this is rather a secondary effect, 

 the result of the death of the cell, which has been already 

 brought about by light. ^ 



' Tliese tannin-vesicles in Mesocarpus are instructive in showin<^ tLe 

 varying effect of light of different colours. Tlius, in red light the tannin- 



