EMBRYOGENY 



219 



evolution ; and finally, it has come not only to no 

 conclusion with the palaeontologists, but has led them 

 towards assumptions which the facts directly contradict. 



(a) The ' biogenetic fundamental principle ' is a 

 mere assumption which asserts that which is to be 

 proved, and does so in contradiction to everything 

 that the actual observations permit of assuming. 



Hackel says himself that in the embryogeny 

 1 mostly ' much is lacking. We can, however, only 

 know whether something is lacking and what it is 

 if, on the other hand, it is clearly established what 

 should be there. That which should be present Hackel 

 must thus have seen in some other quarter, and not 

 in the embryogeny itself ; otherwise we should have 

 had a quite indisputable circle of conclusions. 



The origin of the organisms and this by a quite 

 definite chain of ancestry is therefore assumed here. 

 But whence ? We have given above some of the best 

 known examples which told us something regarding 

 the life of the predecessors and their appearance ; 

 they all, however, without exception, show only what 

 an organism had to contend with when it was already 

 a member of a well-defined type for instance a fish, 

 a crab, a mammal, an amphibian, etc. Of the origin 

 of the Crabs, Fishes, Mammals, etc., we learnt nothing 

 at all. Thereby for instance there might be deduced 

 from a rudimentary gill stage a mammal or a formerly 

 free-swimming larva of a mammal, but not that there 

 were formerly no mammals, but only fish. 



Thus, from the actual observations of the alteration 



