PREFATORY NOTE 



Taxonomy, the art of classification applied particularly to animals 

 and plants, is conditioned largely upon structure. This, we soon learn, 

 is the outcome of experience, the record obverse of history of a bit of 

 life, so that correct taxonomy is reached only as we know the whole 

 story of the object studied. 



From this point of view our art enters the most fascinating, beauti- 

 ful phase of science; every living thing bringing to the observer sug- 

 gestion of some primal, far-off beginning. This must have been! Life 

 pulsates; its forms follow the changes of the physical world; reach a 

 certain maximum as we say, then disappear, reduced to lowest terms, 

 to start again, — more frequently only a cell or two, which wait occa- 

 sion, — good or bad — to repeat the never ceasing cycle. 



As far as possible taxonomy must know these things, and more; 

 for completion? aye for breadth of view; but more rigidly for precision, 

 exactness more or less possibly attained. 



But Nature herself, even in minor things is endlessly inexact, so 

 that for any organism life's highway would seem to have been from 

 the beginning nor straight nor plain. But by this it does appear all 

 progress has been conditioned; endless change of place, of posture, of 

 other environment until now! That the slime mold, a simple, uncov- 

 ered, unprotected, filmy sheet or particle, should, astir with life, — 

 some dominating urge, — should have met all conditions in such good 

 fortune as still to cover the habitable earth in variety, in richness of 

 form, and directness of behavior attracting the attention of the 

 biologist, is a wonder indeed. 



The marvel has been studied; but to modern science the myxomy- 

 cetes are really new; they call for quick taxonomy, possible not to 

 lenses only, but even in so far to the naked eye, and at this moment 

 they kindle lively interest around the world. 



In fact a new chapter here begins, a step forward in the science of 

 our subject. True, we have not been able to open the gate to disclose 

 creation's secret, the earliest cell from which our series rises, but we 

 at last have opened, or at least have set ajar its homologue; we now 

 point to the primal cell through which each new generation passes; 

 we show the history of the germ from which the "cornstock" rises. 

 The gateway for the slime mold small indeed, its width-unit n — the 

 thousandth of a mm.! Yet gate it is, with all the ancient (?) furnishing; 



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