THE MICROSCOPE AND PLANT LIFE 



spongy matter below. A little of this green material 

 may be examined under the microscope and will 

 show us rounded green bodies composed of a sub- 

 stance called chlorophyll. Now chlorophyll is 

 absolutely necessary to all plants, except the fungi 

 and to one or two parasitic plants. It is necessary 

 because, by its aid, plants can build up raw food 

 material into food which will be useful to them. 

 It is not formed in darkness; that is why a board, 

 a roller or any similar object left on a lawn, causes 

 the grass below to turn yellow ; it is the reason also 

 why certain parts of plants, not usually green, turn 

 that colour when exposed to the light. Chlorophyll 

 does not always occur in round globules, sometimes 

 it is found in bands. 



One of the most interesting botanical studies for 

 the microscope is furnished by the leaf of the 

 American water-weed. This plant, which was intro- 

 duced into the country from North America some 

 years ago, has now spread far and wide and is easily 

 obtained. A leaf which is slightly yellowed with 

 age is the best to take for the experiment. It should 

 be cut from the plant, placed at once in a small 

 bottle of water and kept warm for a few hours ; this 

 may be accomplished by keeping the bottle in one's 

 pocket. After a sufficient interval, put a drop oi 

 water in a clean slide, put the portion of leaf in 

 the drop of water, cover with a coverslip and 

 examine with a moderately high power. If the 

 experiment has been properly carried out a won- 

 derful sight will reward us. We shall see that the 



98 



I 



