Organic Connection Between Physical and Psf/chical 281 



Two quotations are all that space will permit us to give 

 for showing what these investigations are bringing out on tiie 

 subject of specificity in behavior. The animals referred to 

 in the first quotation constitute a group of small, arrow- 

 shaped worms known as the Chaetognatha — bristle- jaws. 

 "Each species occurring in the San Diego region has its own 

 definite and specific manner of vertical distribution, just as 

 truly as it has its own morphological cliaracteristics." -^ 



Similar results have been obtained by the same methods 

 applied to a very different group of animals, minute crus- 

 taceans of the ubiquitous order Copepoda. The investiga- 

 tions on this group have been made by Dr. C. O. Esterly, 

 and the results are specially interesting in this case, because 

 Doctor Esterly has applied laboratory experimentation, to 

 some extent, to the same animals, and has found a good de- 

 gree of concordance in the results of the statistical and the 

 experimental investigations. *'A heterogeneous assortment of 

 forms may be obtained in the same collection but each has its 

 own way of reacting toward the elements of its environ- 

 ment." 23 



It is the indubitable trend in one direction of the vast 

 evidence from these three quite different classes of research 

 on animal behavior that to my mind justifies such a con- 

 ception of specificity of psychical and reactive animal life 

 as that formulated above. Something of the probable mean- 

 ing of this specificity we shall see in the next chapter. 



REFERENCE INDEX 



1. Loeb ('02) 189 13. Huxley, J. S 15G 



2. Morgan, C. L 10 U. Darwin, C I, 353 



3. Royce 328 15. Kellogg, V. I litS 



4. Royce 329 16. Nature Lovers' Library II, 218 



S.Holmes ('11) 92 17. Nature Lovers' Libnirv 



G.Holmes ('11) 93 III 100 



7. Peckham, G. W. and E. S. 53 IB. Seton I, 3«)0 



S.Holmes ('11) 21 19. Groos 15 



9. Jennings ('OG) 49 20. Wheeler ('10) 518 



10. Holmes ('11) 95 21. Hitter ('IS) 119 



1 1 . Wallace, A. R 555 22. Michael 4G 



12. Huxley, J. S 151 23. Esterly 11 



