THE BREATH OF LIFE 



there develops a pale, smooth, solid, semi-transpar- 

 ent sphere, the size of a robin's egg, dense and suc- 

 culent like the flesh of an apple, with the larvae of 

 the insect subsisting in its interior. Each of these 

 widely different forms is evoked from the oak leaf 

 by the magic of an insect's ovipositor. Chemically, 

 the constituents of all of them are undoubtedly the 

 same. 



It is one of the most curious and suggestive 

 things in living nature. It shows how plastic and 

 versatile life is, and how utterly unmechanical. 

 Life plays so many and such various tunes upon the 

 same instruments; or rather, the living organism is 

 like many instruments in one; the tones of all in- 

 struments slumber in it to be awakened when the 

 right performer appears. At least four different 

 insects get four different tunes, so to speak, out of 

 the oak leaf. 



Certain insects avail themselves of the animal or- 

 ganism also and go through their cycle of develop- 

 ment and metamorphosis within its tissues or or- 

 gans in a similar manner. 



On the threshold of the world of living organisms 

 stands that wonderful minute body, the cell, the 

 unit of life — a piece of self-regulating and self-re- 

 newing mechanism that holds the key to all the 

 myriads of living forms that fill the world, from the 



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