BIOLOGY FOR YOUNG BEGINNERS. 



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oxygen to the air again. Thus he works from sunrise to sunset. His 

 hours are regulated by the sun, instead of by Congress. You never hear 

 of an " eight-hour movement " or a "strike" among the chlorophyll 

 laborers. As soon as the sun goes down they go to bed, like honest 

 workmen. During the night, while these green-leaf or chlorophyll 

 workers are asleep, the colorless protein-jelly of the cell gives out the 

 poisonous carbonic acid and takes in oxygen. The green cells give 

 off carbonic acid and take in oxygen during the day, as well as during 

 the night, but the little chlorophyll-grains do so much more work than 

 the rest of the jelly in the cell, it seems as though the cell gives out 

 nothing but oxygen and takes in nothing but carbon during the day, 

 when all these little colored chemists are doing their best. 1 



Now you can understand why it is healthy to have growing plants 

 in your room during the day, but not during the night. When the 

 sun is shining they purify the air, because they give off more oxygen 

 than carbonic acid ; but at night they poison the air, because they 

 give off only carbonic acid. 



All plants that contain this green-leaf matter, or chlorophyll, are 

 called green plants. You remember the colorless plants, such as toad- 

 stools, are called fungi. It is found, as you have seen, that green 

 plants must have the sunshine, but fungi grow as well, or even bet- 

 ter, in the dark. Thus we have found the materials out of which 

 the mould-cell is made, and the use of all its different parts. Who 

 would have thought there was so much to learn in one of those little 

 bladders, when you first looked at it under the microscope ! This 

 green mould-plant has a very pretty name of its own protococcus. 

 The word means first berry. Perhaps this name was given because 

 these cells look like little berries. 



i First partition. 



I Partition-wall. 

 Fig. 7. "Fission" of the Cell. 



Ill 111 In 



lili llfflBBJ Second partition. 



Fig. 8. One Cell divided into Foue. 



If you look long and carefully, you can see the protococcus or 

 berry-cell begin, like a little carpenter, to make a partition-wall right 

 through the middle of the old house (Fig. V) ; and, when the wall is 

 finished, the two halves move away from each other, the carpenters 



1 Recent investigations seem to prove that the breathing of plants is similar to that 

 of animals during both day and night ; that the breaking up of carbonic acid is diges- 

 tion, and not respiration. It has its seat in the chlorophyll, and is active in the sun- 

 light ; while the respiration, the breathing in of oxygen and the breathing out of car- 

 bonic acid, has its seat in the protoplasm, or protein of the cells. (See "Respiration of 

 Plants," by Emile Alglave, Popular Science Monthly for November.) 



