﻿389 



troversy. I cannot give further space here to theoretical discus- 

 sions of this sort and am obliged to refer any persons interested 

 to my other works, especially " The Genesis of the Arietidae " and 

 the " Bioplastology, the related Branches of Research,"* in which I 

 have more fully given my own views. 



The exclusive Darwinians are, according to the views of the 

 Neolamarckians, as much out of the true path in one direction as 

 are the empiricists in the other in appealing exclusively, as they 

 often do, to the action of the surroundings in accounting for 

 observed modifications. 



It is certainly not a very acute analysis of the facts which attrib- 

 utes to external causes exclusive power in producing modifications 

 in many cases as has been largely done by experimental zoologists. 

 For example, Brauer and the author have both pointed out this de- 

 fect in the accepted explanations of the famous Schmankewitsch 

 experiments upon Artemia, and the same may be said of the ex- 

 planations of all experimenters who do not take into account the 

 internal reactions of the organisms themselves. 



The physical forces of the surroundings must act through medium 

 of entergogenic movements, and this is shown clearly in the nature 

 of modifications produced which are extra growths, substitutions of 

 characteristics due to changes of functions, etc., or partial or abso- 

 lute obliteration of these due to the failure of genetic force to re- 

 peat characteristics in the presence of opposing influences and super- 

 imposed characteristics as in accelerated development. 



Ctetology should also, however, include the study of the action 

 of physical forces, when they either actually do produce direct effects 

 upon organisms or may be assumed to act in this way. Changes in 

 light, food, heat and moisture may cause modifications that cannot 

 be included under the head of entergogenic reactions without dan- 

 ger or confusion. 



Maupas gives exceedingly instructive examples of this class, and 

 quotes other authorities who have investigated these effects in Pro- 

 tozoa. 



Beddard gives a number of examples of such modifications in 

 his Animal Coloration, and Semper has also discussed the same sub- 

 ject more extensively in his Naturlichen Existenzbedingungen der 

 Thiere.\ 



* Smithsonian Contributions, No. 73, and Proc. Bast. Soe. Nat, Hist., xxvi. 

 f Translation by Minot, Macniillan, 1892. 



