THE BEGINNINGS OF LIFE. 617 



The opposing notion that all the forms of life 

 which at present exist — including the structureless 

 Amoeba and the insignificant Mucor which now springs 

 up on decaying substances — are direct lineal descendants 

 of organisms which lived, ages before the birth of man, 

 in far distant pre-Silurian epochs, seems to me opposed 

 to all reason, from the point of view of the evolutionist ^ 

 But that a great amount of similarity should exist 

 between the earliest forms of organisms which have 

 appeared in intervening epochs and those which exist 

 at the present day — whether amongst Cryptogams, Fora- 

 minifera, Mollusca, or other animals — is not so much 

 to be wondered at when we recollect that the starting- 

 point or primordial constitution of living matter has 

 ever been generically the same, that the internal deter- 

 mining causes of change have been constant, and that 

 the sum-total of surrounding conditions have probably 

 not been more various than we might be warranted in 



fore, form the links of a continuous chain from the monad to the man. 

 They are all equally co-existent, independent, and unconnected with 

 each other, like the extreme peripheral buds of a tree of life, whose 

 base is largely concealed or consumed in the earth, but whose more 

 recent branches can be readily traced through all the surviving fossili- 

 ferous strata of the globe. Such ramifying trees of life, however, have 

 never ceased to originate and develop de novo in the same mode as the 

 first, since the first found a suitable habitat ; and it is neither necessary 

 nor philosophical to assume that any animal" type had a differait mode 

 of origin from that of another — the durability of a type being the best 

 proof of its natural origin.' ('An Outline of Recent Zoology,' i86t, 

 p. 9.) See also an allusion to the more recently published views of Mr. 

 G. H. Lewes on the same subject, at p. 75. 

 1 See p. 5S9. 



