SPECIAL CREATION OR DERIVATION? 



turn were the slowly modified descendants of 

 still less complex plants and animals, and so on 

 until we converge to those primitive organisms 

 which are not definable either as animal or as 

 vegetal, but which in their lowest forms are 

 mere shreds of jelly-like protoplasm, such as the 

 spontaneous combination of colloidal clusters 

 of organic molecules might well be capable of 

 originating under appropriate conditions, after 

 the manner pointed out in the preceding chap- 

 ter. The agencies by which this slow derivation 

 of higher from lower forms has been effected are 

 agencies such as are daily seen in operation 

 about us ; namely, individual variation, adapta- 

 tion to environing circumstances, and hereditary 

 transmission of individual peculiarities. Obvi- 

 ously such a hypothesis is not only highly credi- 

 ble in itself, since it only alleges that the growth 

 of a complex organism from a simple globule of 

 protoplasm, which is accomplished in every case 

 of individual evolution, has also been accom- 

 plished during the evolution of an immensely 

 long series of individuals ; but it is also a purely 

 scientific hypothesis, since it appeals to no agen- 

 cies save such as are known to be in operation, 

 and involves no assumptions which cannot, 

 sooner or later, be subjected to a crucial test. 



These preliminary considerations show how 

 strong is the legitimate presumption in favour 

 of the theory of derivation. But the case is not 

 377 



