100 PRINGSHEIM^S RESEARCHES ON CHLOROPHYLL. 



The subject is one tlemnnding investigation, and further 

 communications will be given. 



2. The ground- svhsiance of the chlorophyll-corpuscles 

 and its included substances in intense light. — The chloro- 

 phyll-corpuscles serve not only as organs of assimilation, 

 as has hitherto been supposed, but also as organs of respi- 

 ration. This, their double function in gas interchange, is 

 evidenced by the morphological and microchemical chauges 

 ■which their ground-substance and contained-bodies undergo 

 in intense light. Though green organs under the influence 

 of light give off oxygen, yet the chlorophyll-corpuscles, by 

 reason of their structural and chemical characters, fix oxygen 

 in a high degree and at once transfer it to the forming pro- 

 ducts of assimilation. The physiological value of these 

 substances, formed and deposited within the chlorophyll- 

 corpuscles, falls therefore to be considered after the beha- 

 viour in oxygen and in light of the bodies themselves. 



The ground-substance of the chlorophyll-corpuscles and 

 masses after insolation resembles in appearance the condition 

 in which it is left after alcohol or other solvent has decolorised 

 and removed the oil from it. It is a colourless skeleton, 

 unchanged in form, and presents the same sponge-like 

 structure already described as resulting from the action of 

 solvents, acids, and moist warmth (figs. 1, 3, and 26). In 

 Spirogyra the marginal projections on the band (so change- 

 able in the living cell) remain ; only sometiuies when 

 an excess of heat has operated, or a considerable time has 

 elapsed before the death of the band, are the projections 

 withdrawn and the band contracted in width, or the margins, 

 still marked by the projections, become levolute. Chemi- 

 cally little can be said. The skeleton shows a protoplasmic 

 character, and takes up iodine and colouring agents more 

 readily than before, possibly on account of its porosity. 

 Insolation, however, produces a change in the nature of the 

 substance, in virtue of which it offers greater resistance to 

 external influences. Such a change is well illustrated by 

 the case already described of Nitella-Ckt\i^ killed by rapid 

 insolation of a limited area, in which the decolorised chloro- 

 ])hyll-corpuscles of the insolated area remain unci.anged in 

 form and shape long after the green corpuscles and contents 

 of the non-illuminated portion of the cell are completely dis- 

 integrated (fig. 24). The chlorophyll-bands of Spirogyra and 

 the chlorophyll-masses of other plant-cells, which, as is 

 known, are extremely sensitive to injurious influences, such 

 as increase of temperature, mechanical irritation, &c., losing 

 their form, contracting, rupturing, or swelling into variously- 



