EDWARD COPE 81 



and premolars. Now the foetal state of the existing 

 Camel shows us a cannon bone divided as in the 

 Pcebrotherium and, on the other hand, incisors as in 

 the Protolabis ; very young camels at the present 

 possess also the additional premolar of a Pliau- 

 chenia, rarely found in the adult camel. 



This brings us back, with very little alteration, 

 to the law of Haeckel regarding the parallelism of 

 the embryological and of the palaeontological de- 

 velopment of beings. But Cope protests vigorously 

 against too exclusive an application of this law, 

 and appeals, with good reason, to the compulsory 

 checking of palaeontological evidence. 



The reason for this distrust of the indications 

 furnished by embryonic development is to be found 

 in an original philosophical conception, on which 

 the American scholar dwells without ceasing, and 

 which is, so to speak, his guiding idea in the study 

 of the phenomena of evolution. This is that 

 evolution has been progressive or regressive, as the 

 case requires ; in other words, the modifications of 

 structure have been produced, sometimes by the 

 addition, and sometimes by the subtraction of organs 

 or parts of organs. When we find ourselves con- 

 fronted with rudimentary organs, such as fingers, 

 limbs, fins, or teeth, it is often difficult to decide 

 whether we have to do with persistent primitive 

 conditions which permit these types to be con- 

 sidered as the ancestral forms of existing beings, 

 or if, on the contrary, these reductions of organs 

 are the result of degeneration, and consequently 

 have a relatively modern origin. The beings 

 presenting these characteristics may be, in a word, 

 G 



