THE THEORIA GENERATIONS. 277 



the younger Meckel in 1812 and used for the purpose of refut- 

 ing some of Oken's erroneous views on the development of 

 the alimentary tract. 



In general it may be said that the effect of Wolff's work on 

 his contemporaries was anything but immediate. 1 There are 

 writers who even doubt the truth of the oft-repeated statement 

 that Wolff refuted the theory of predelineation. Sachs, e.g., 

 speaking of Wolff's Theoria, says that the "weight of his argu- 

 ments was not great" and that "the hybridization in plants 

 which was discovered at about the same time by Koelreuter 

 supplied much more convincing proof against every form of 

 evolution." 2 We cannot lay much stress on this statement, 

 which seems to imply, what some physiologists seem never 

 to tire of implying, that evidence derived from experiment is 

 eo ipso more convincing than evidence derived from observa- 

 tion. It is certain that the predelineationists had considered 

 the case of hybrids, for did not the ever-watchful Bonnet 

 endeavor to explain the origin of the mule on the assumption 

 of emboitement ? And why should Koelreuter's plant hybrids 

 have more value in refuting emboitement than that commonest 

 of all hybrids, the mule ? If Sachs wishes to imply that at the 

 present day we should regard the evidence from hybrids as a 

 complete and satisfactory refutation of the theory of emboite- 

 ment, we may assent ; but this is not tantamount to saying that 

 in the latter half of the eighteenth century it was Koelreuter 

 and not Wolff who refuted the theory of evolution. Perhaps 

 it would be better to leave this question of the relative merits 

 of Wolff and Koelreuter to the student who has the time and 

 the opportunity to study all the relevant literature of the clos- 

 ing decades of the eighteenth century. 



Wolff's position in the history of thought on the subject of 

 organic development becomes somewhat clearer when we com- 

 pare him with Darwin, for whose coming he helped to prepare 



1 " Though every reader of the Theoria Generationis must see that Wolff 

 triumphantly establishes his position, yet, seventy years afterwards, we find even 

 Cuvier (Histoire des Sciences Naturelles) still accrediting the doctrine of his 

 opponents." Huxley, The Cell Theory. 



2 Sachs. History of Botany, p. 405. 



