2 20 BIOLOGICAL LECTURES. 



pitfall. They all faced the question of preformation, and dis- 

 covering no natural way by which the germ could come ready- 

 made, they insisted that the germ must start anew every time 

 and from the pit of material homogeneity, acquiring everything 

 under the guidance of hyperphysical agencies, assisted by the 

 accident of external conditions. 



It is most instructive to recall with what persistence this 

 dogma of formless homogeneity maintained itself, ever on the 

 alert to challenge the most distant suggestion of anything that 

 pointed to reconciliation with its old foe, preformation. ^ 



While the epigenesist of the old school could not tolerate 

 even so much as a " quasi-preformation " of any description, 

 the epigenesist of to-day has become so familiar with the reality 

 of preexistent germs that he now comes forward claiming that 

 the ovum actually represents "« highly complex organization!' 



What then is the standpoint t Is it that of preformation or 

 of post-formation, or of some higher ground, reconciling both 

 aspects of the subject >. The answer has already been antici- 

 pated. Our position involves the old standpoints, but not as 

 they stood in antagonistic separation, but as they stand in 

 union after a century's revision and amendment. Both pre- 

 formation and post-formation, as now understood, enter into 

 every theory of development. Taking the words in their old 

 sense, we should have to abandon both. We cannot affirm 

 that the parts of the adult organism are preformed as such ; 

 we can only say that of the germ, as something which is not 

 produced epigenetically, but comes ready-made. Neither can 

 we affirm that development is post-formation independent of 

 any predetermining organization. 



The old conceptions thus revised furnish the basis for an 

 entirely new standpoint. The question is no longer whether 

 all is preformation or all post-formation ; it is rather this : 



1 " Wenn hingegen andre, um die Evolutionshypothese mit der Lehre von der 

 allmahlichen Bildung zu vereinbaren, zwar zugeben, dass der Zeugungstoff nicht 

 praformirt sei, aber doch meinen, dass er dessen ungeachtet einen Keim enthalte, 

 der dennoch was anders sei, als ungeformter Zeugungstoff, so sind das unbestimmte, 

 leere Ausdriicke. Wenigstens geht mir es dann mit solchen Quasi- Keimen, wie 

 dem Cicero mit dem quasi corpus des Gottes der Epicuraer, wovon er sagt : 

 ' Corpus quid sit intelligo : quasi corpus quid sit, nullo prorsus modo intelligo.' " 

 Blumenbach: Handbuch der Naturgeschichte, 1830, p. 12. 



