150 THE MICROSCOPE AND ITS LESSONS. 



measure more than half an inch in length by a quarter 

 of an inch in breadth, you will observe a vast number of 

 little openings lying over the whole of the skeleton ; for 

 you must understand that the fleshy part of these leaves 

 has been removed, that we might learn how a plant 

 breathes. Wordsworth sings as a poet 



" And 'tis my faith that every flower 

 Enjoys the air it breathes." 



I cannot tell you whether a flower enjoys sensation. I 

 can tell you that it possesses the virtue of punctuality; so 



\W.G.S.AD.NA7 F X..3Z6. 



Portion of leaf, showing cellular tissue and stomata. 



much so that a floral clock has been constructed, com- 

 posed of English wild flowers, arranged on the principle 

 of the rest, or sleep, which all plants are known to take 

 every twenty-four hours, each flower, being suspended 

 over the figures on a dial, opening or closing punctually 

 at the time indicated by the hour. I can tell you also 

 how very nearly these little openings on the epidermis 

 of our box-leaves resemble the air-cells in your lungs 

 and mine, in which as many as 600 millions have been 

 reckoned, distributed amongst 18,000 air-tubes. Equally 



