CHAPTER III 



Descriptive hiologij. Development of plmits and animals; of 

 sex, and sexual reproduction, and alternation of genera- 

 tions. The path of vertebrate evolution. 



Science as we have seen is cosmopolitan and impossible 

 of limitation by geographic lines. Especially is this true of 

 descriptive biology. With the increasing specialization of 

 modern science it is to a certain extent possible for one man 

 or a group of men to work out more or less independently 

 some particular problems or group of problems of far-reach- 

 ing interest and importance. Thus our knowledge of animal 

 reactions we owe largely to Jennings, Rhumbler, Mast and 

 Loeb; the physiology of digestion immediately calls to mind 

 the epochal work of Pavlov, while Chittenden's researches 

 have made scientific nutrition matter of household knowledge. 

 The new science of genetics we owe largely to the work of 

 Bateson, Punnett, Cuenot, Castle, Davenport and Morgan, 

 while the structure and function of the cell, have been in great 

 part unraveled by the skillful touch of Wilson and Boveri. 

 To a certain extent this is likewise true of purely descriptive 

 biology. Amphioxus and the name of Willey are indissolubly 

 linked together in our minds ; the oyster has been exhaustively 

 studied by Brooks, the alligator by Reese, the Ascidians by 

 Ritter and the crayfish by Andrews. We have the splendid 

 researches of Allen, Merriam and Stone on the classification, 

 distribution and habits of birds and mammals; those of Jor- 

 dan, Dean and Eigenmann on fishes, of Mayer on Medusae and 

 of hosts of other specialists on various groups of animals and 

 plants; while the names of Osborn, Cope and Scott will ever 

 be associated with the extinct life of ages long gone by. 

 Many of these studies however are of but small value in 

 themselves. Information as to the structure, classification and 

 distribution of a given organism or group of organisms, gives 

 us comparatively little information as to the great laws of life, 

 except in so far as these facts are correlated with similar facts 

 relative to other groups of organisms, whereas the research 

 in physiology (using this term in its broadest sense) of a single 

 man, may lead to discoveries of profound and far-reaehing 



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