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THE AMERICAN NATURALIST [Vol. XLY11 



mens of each species obtained, instead of publishing only 

 data relative to successful hauls and recording the 

 species as abundant or rare, many problems now so 

 largely discussed from hypothetical points of view could 

 be analyzed entirely on a factual basis without involving 

 committal to any hypothesis whatsoever. For instance, 

 by such means it would be possible: 



1. To measure the degree of variation in the habits of 

 distribution of species. 



2. To measure the extent of correlation between varia- 

 tion in the vertical distribution of species and variation 

 in their horizontal distribution. 



3. To measure the degree of correlation between 

 morphological and ecological characteristics of species, 

 and so arrive at an accurate analysis of the causes of 

 adaptation. 



4. To measure the range of adaptation accompanying 

 the same structures. 



5. To measure the range of variation in structure 

 adapted to the same environmental conditions. 



6. To analyze the natural behavior of a species with- 

 out involving the necessity of first placing collected indi- 

 viduals under the artificial conditions of the laboratory 

 and then reading the results, arrived at by experiment, 

 back into their natural environment. I do not wish to 

 minimize in the least the immense value of laboratory 

 experiments on behavior, but, no matter how great the 

 achievement, such experiments can not afford a reliable 

 basis for interpreting the natural behavior of a species 

 until it becomes possible to re-create nature in miniature. 



While these are but a few of the problems that are 

 urgently calling for solution, I can not help but feel that, 

 in the foregoing pages, we have touched the fringe of a 

 line of quantitative investigation destined to yield much 

 of importance to the student of evolution. 



BIBLIOGRAPHY 



Aida, T. 



'97. The Chsetognatha of Misaki Harbor. Annot. Zool. Japon., Vol. 1, 



