1 6 SCIENCE PRIMERS. [iv. 



(e) In the green parts of plants the protoplasm 

 undergoes a peculiar change, by which it is broken up 

 into granules which contain the green colouring 

 matter (chlorophyll). These granules are accordingly 

 termed chlorophyll granules. 



1 6. Chlorophyll granules, consist then of proto- 

 plasm coloured green by a pigment called chloro- 

 phyll. They abound in the superficial cells of plants, 

 and their colour being seen through the thin cell-walls, 

 give the green hue to leaves ; similar granules tinged 

 with other colours give in some cases the bright 

 tints to flowers. Chlorophyll under the influence 

 of sunlight brings about changes in the cells of the 

 leaf that result in starch being formed and distributed 

 all through the plant, as required. In so doing, it 

 is supposed that the chlorophyll separates the carbon 

 from carbonic acid taken from the air, gives back 

 the oxygen to the air, and supplies the carbon (which 

 at the same time combines with the components of 

 water to form starch) to the plant. It is a curious 

 fact that chlorophyll is not developed, and there- 

 fore that this process will not go on, except the 

 plant be supplied with iron ; and as all soils contain 

 iron> the plant can always take this substance up 

 by its roots. In the absence of sunlight also, the 

 green colour of chlorophyll does not appear, hence 

 celery is covered up to make it white, otherwise it is 

 a very green plant. 



17. Starch. This compound of carbon, hydrogen 

 and oxygen abounds within the cells of many parts 

 of many plants, as the potato and all cereal grains, 

 arrow-root, tapioca, sago, &c. It consists of white 

 granules, differing in form in different plants (Fig. 6), 



