418 M. W. Veltmann on the Descendence- Theory 



influence in very fertile animals, therefore in such as lay 

 thousands of eggs. 



Whoever endeavours to elevate the Dai-winian doctrine 

 from a very general and indefinite hypothesis into a scientific 

 theor}^ must therefore at any rate always take the above point 

 into consideration. He must arrange his "genealogical tree" 

 only in such a manner that all the ramifications which issue 

 out of any given branch possess a longer duration of life than 

 the latter. 



Paleeontology furnishes us something actual in connexion 

 with the sequence of species. In general it does not agree 

 with an increase in the duration of life. The insects which 

 for the most part, like summer plants in the vegetable king- 

 dom, are extremely short-lived, were preceded by Polyps, 

 Mollusca, and Crastacea ; and although Ave cannot now ascer- 

 tain how long a Graptolite or Trilobite of the Silurian 

 formation lived, it can hardly be supposed that the insects 

 have originated from animals with a shorter vital period. 

 This could be possible only if Mollusca, Insecta, &c. origi- 

 nated from a common short-lived stem. But where, then, 

 would the side-line have remained which led up from this 

 stem, by the Mollusca &c., to the Insecta? How can it have 

 come about that nothing of it is preserved, whilst of the Mol- 

 lusca and Crustacea innumerable petrified examples exist? 

 Moreover experience teaches us that even the lowest animals, 

 polyps, rhizopods, &c., possess a longer diu'ation of life than 

 the insects, and also exceed them in fertility. 



The case is the same with the Mammalia. With certainty 

 we can scarcely ascribe to these an earlier than Tertiary 

 origin. Fishes and reptiles preceded them ; and they can 

 only be regarded as produced from the latter. But reptiles in 

 general live longer than mammals. Among tortoises we have 

 examples of an age of more than 200 years, whilst the most 

 long-lived of terrestrial mammals, the elephant, is rather more 

 than 100 years old. 



Darwin, on the foundation of his h}^50thesis, describes the 

 demonstration of the production of a peculiarity injurious to 

 the animal as destructive of the hypothesis. F. Midler, in 

 his work ' Fiir Darwin,' calls upon opponents to indicate any 

 one among the great number of natural-history facts which is 

 incompatible with Darwin's opinion. He regards the circum- 

 stance that this has not yet been done, even by the observers 

 who are most familiar with the animal world, as a proof of 

 the Darwinian doctrine. But so long as the latter is nothing 

 more than a mere hypothesis, containing only the most 

 general outline of a theory, definite facts can no more be 



