II 



LIVING MATTER 



experiment being carried out in a glass jar (as shown in Fig. 14),. 

 the plant, under the influence of light, will develop normally, 

 flower, and bear fruit. If the iron sulphate 

 is wanting in the solution, the plant may 

 live for some time, but its leaves will be 

 colourless, and under the microscope show- 

 absence of chlorophyll; if the other salts 

 are wanting, the plant will not germinate, 

 or perishes as soon as it develops. 



This experiment proves that all the 

 carbon assimilated by the plant is derived 

 from the carbonic acid of the air the 

 grand discovery of Ingenhousz ; further,' it 

 shows that the assimilation of carbon is 

 conditioned by chlorophyll, the molecules 

 of which contain iron ; lastly, the assimila- 

 tion of nitrogen is due to the reduction 

 of nitrates, and the assimilation of sulphur 

 and phosphorus to the reduction of sulphates 

 and phosphates. 



The intimate processes by which the 



plant succeeds, by the assimilation of all 



these elements, in synthetically forming 



organic substances are for the most part 



unknown. Thanks, 



however, tO the WOrk Of FIG. 14. Zea mais in culture 

 wa Irnnw nmo solution. Mg., grain of maize; 



, We knOW SOme- S n., Sachs 1 nutrient solu- 



of the process of tion ; * cork to su PP r t plant 



f . in vertical position. 



starch formation in the 



green parts, which may be taken as the starting- 

 point for all other synthetic processes in plants. 

 In the adult cell, chlorophyll is contained within 

 special ellipsoidal corpuscles known as chloro- 

 plasts, which are for the most part found in 

 great numbers heaped against the parietal proto- 

 plasm (Fig. 15). After a green plant has been 

 exposed for a few minutes to full sunlight, 

 starch granules are seen to appear in the middle 

 or edge of the chloroplasts, which gradually 

 increase in size until their volume exceeds that 

 of the chloroplasts. During the night, when 

 mation is suspended, this accumula- 

 tion is dissolved by the action of diastatic fer- 

 ments, and conveyed under the form of sugar 



to the parts in which it can be utilised as food material. 



Starch represents the principal nutritive reserve material that 



accumulates in a solid form in the plant cells in which it is formed. 



FIG. 15. Two" leaf-cells of 

 Funaria hygrometrica. 

 d, chloroblasts ; n, starch 

 nucleus. Magnification, 

 300 diameters. 



