Packahd] insects OF THE PLANT HOUSE. 109 



or a Humboldt? Simple as the process appears to our eyes, 

 the determinuig cause is still an uufathomed myster3\ The 

 humble truth-seeking observer can only ponder and work on, 

 hoping that the solution may be possible to his race. Cer- 

 tainly all is not known, when with some naturalists and phi- 

 losophers we attempt to settle the question by saying that life 

 is a I'unction of protoplasm ; though it is granted that life on 

 this globe does not exist without it. For protoplasm is po- 

 tentially a very variable substance, and life a problem quite 

 beyond the science of our day to settle, whatever may be the 

 flood of light thrown upon the question by modern science. 

 The life force existing in protoplasm is powerless witliout an 

 Infinite intelligence and will urging it on in its destined 

 channels, just as muscular force is subject to the finite will 

 that calls it forth. Though muscular force is a function of 

 muscle, that does not account for a muscular act, nor does 

 the nerve cell or fibre account for a nervous act ; both are 

 impelled by a will force not of themselves, as INIatthew Arnold 

 would say. So at the outset all life may have been the re- 

 sult of chemico-physical forces, producing from its elements, 

 and acting upon the compound thus produced, which we call 

 protoplasm. Still this act of "spontaneous" generation was 

 none the less under the guidance of an all-pervading intelli- 

 gence and will. S[)ontaneous generation is not self-creation. 



So the study of our little Aphides ends in starting a series 

 of questions that haunt us each step we take, some of them 

 the largest that baffle the human reason. Certainly the mind 

 of the naturalist need not grow rusty. Problems of matter 

 and life and spirit assail him on every side, and the calm- 

 ness, patience and breadth of conception their consideration 

 involves are a fitting preparation for encountering the prob- 

 lems of his own existence. 



Our studies over, now arises a practical (piestion. How 

 shall we exterminate these troublesome pests? In dealing 

 with these insects in the hot house, where there are no insect 



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