2o8 BIOLOGICAL LECTURES. 



ment might have appeared more serious. As it is, however, 

 the attempt to identify epigenesis with the interests of research 

 is scarcely more successful than Bourne's effort to credit it 

 with a monopoly of "fact." An author who can accept the 

 hypothesis of " Intracellular Pangenesis " ^ of Hugo de Vries 

 and the theory of migrating pangen-determinants, is not so far 

 from the perilous " Ruhekissen." ^ 



Hertwig ^ is no less emphatic than Bourne * in asserting that 

 His, Weismann, and others occupy the standpoint of the old 

 evolution. Bourne, persevering with his thesis, epigenesis a 

 fact, not a theory, declares that " the evolutionary theories 

 which have lately been put forward are not, therefore, of the 

 nature of a general statement of fact, but are assumptions 

 made in order to explain the causes of observed phenomena ; 

 they are dependent npon reason, not on observation'' (p. 114). 

 Both Hertwig and Bourne point out some fundamental distinc- 

 tions between the old and the new evolution, and yet they 

 assert that there is an essential likeness of standpoints. To 

 some extent this comparison of standpoints has been sanc- 



1 Die Zelle tmd die G ewe be, 1892, p. 287. 



2 " From our standpoint also," says Hertwig, "we require for the explanation 

 of the development-process in different species of organisms different kinds of 

 germ-substafice with an extremely high organization, by virtue of which they react 

 in a specific manner {i.e., in a manner corresponding to their kind), and in the 

 finest way, to all external and internal stimuli." {Zeit- und Streitfragen, p. 131.) 



To make the concession somewhat stronger, Hertwig indorses the following 

 from Nageli : "Egg-cells just as well as fully developed organisms possess all the 

 essential characters, and organisms differ from one another as egg-cells, not less 

 than in the developed condition. In the hen's egg the species is contained as 

 completely as in the hen, and the hen's egg is as different from the frog's egg as 

 the hen from the frog." 



8 Referring to Weismann, Hertwig remarks : " Somit waren wir denn in etwas 

 veranderter Weise auf dem Standpunkt der Evolutionisten des vorigen Jahrhun- 

 derts angelangt, nach welchem der Keim das ausserordentlich kleine Miniaturbild 

 des ausgebildeten Geschopfes sein soil " {Zeit- und Streitfragen, p. 10). Of His 

 he says: "Am meisten hat His das Problem der Entwickelung im Sinne der 

 alteren Evolutionstheorie in mehreren entwickelungsgeschichtlichen Schriften zu 

 losen gesucht " {Aeltere und Neuere Entw.-Theorien, p. 16). 



* Bourne {Science Progress, April, p. 107) says : " It is certainly a striking fact 

 that the most minute and elaborate researches of the last few years have led the 

 course of biological speculation back to the point of view of Haller and Bonnet in 

 the i8th century, and have threatened to discredit altogether the opposite doctrine 

 of epigenesis." 



