MONISTIC EVOLUTION 139 



a single cell, remained together, and now began 

 gradually to perform different offices of life. 



But this is a mere vague analogy. It does not 

 represent anything actually occurring in nature, 

 except in the case of an embryo produced by some 

 animal which already shows all the tissues which its 

 embryo is destined to reproduce. Thus it establishes 

 no probability of the evolution of complex tissues 

 from simple cells, and leaves altogether unexplained 

 that wonderful process by which the embryo-cell not 

 only divides into many cells, but becomes developed 

 into all the variety of dissimilar tissues evolved from 

 the homogeneous egg, but evolved from it, as we 

 naturally suppose, because of the fact that the egg 

 represents potentially all these tissues as existing 

 previously in the parent organism. 



But if we are content to waive these objections, 

 or to accept the solutions given of them by the 

 appearance and disappearance argument, we still 

 find that the phylogeny, unlike the ontogenesis, is full 

 of wide gaps, only to be passed per saltum, or to be 

 accounted for by the disappearance of a vast number 

 of connecting links. Of course it is easy to suppose 

 that these intermediate forms have been lost through 

 time and accident ; but why this has happened to 

 some rather than to others cannot be explained. In 

 the phylogeny of man, for example, what a vast hiatus 

 yawns between the ascidian and the lancelet, and 

 another between the lancelet and the lamprey ! It is|j 



