MICRO-ORGANISMS 



means, for Professor A. D. Cockerell of 

 the University of Colorado has found fos- 

 sil tsetze flies in the Miocene strata of 

 Colorado, and Professor H. F. Osborn of 

 Columbia University has made a similar 

 discovery in the tertiary strata of the same 

 region. And so we will find the evidence 

 accumulating that " the everlasting hills " 

 themselves will not last nor be as abiding 

 or unchangeable as are many unicellular 

 forms of life. 



This unchangeableness of certain forms 

 of life through unimaginable antiquity is 

 impressively illustrated by those unicellu- 

 lar algee called Diatoms, whose survival 

 may be largely due to the indestructible 

 case of flint which each individual of them 

 forms about itself. Here we find that in- 

 scrutable, sticky thing called protoplasm 

 fashioning coverings for itself of the most 

 varied and exquisite patterns in Nature 

 made out of pure silex, some in spheres, 

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