No. 529] 



ORGANIC RESPONSE 



and the second series of experiments in synthesis is sufficient warrant 



Tennent arranged a series of hybridizations of Echino- 

 derms at Tortugas which yielded data of great interest in 

 connection with the earlier conclusions of Vernon, Don- 

 caster, and Herbst as to the influence of temperature and 

 season changes upon dominance. From the information 

 derived from crosses of Hipponoe and Toxopneustes it is 

 Hear that the dominance of the parental characters is 

 dependent upon the alkalinity or the concentration of the 

 OH ions. The products of the trial cross fertilization, 

 however, were not reared to maturity. 18 



No phase of the subject under discussion is more 

 readily amenable to experimental investigation, and no 

 results may be expected to bear more directly on the 

 mechanism of inheritance than those in which similar 

 unions give dissimilar progenies under the pressure of 

 unlike environments. It is to be noted that everything 

 of value with regard to the influence of environment 

 upon hybridizations has been secured by the introduc- 

 tion of the geographic or climatic element, that is, the 

 unions leading to divergent results have been made in 

 habitats in which the environic complexes differed not in 

 one, but in many features. Thus the climatic components 

 in southern Mexico reach dissimilar maxima and minima, 

 and run unlike courses from those of Arizona. 



This method of transplantation of organisms to dis- 

 tant localities furnishing congeries of climatic factors 

 markedly different from those of the habitat in which 

 they were found is one which offers opportunities of the 

 broadest kind, and such exchanges have been made be- 

 tween fresh and salt water, cave and surface, alpine 



