CONCLUSION 223 



have conducting tissues which partly answer 

 the same purpose. Among the Liverworts, 

 especially, there are some very simple plants, 

 which may be compared to a Fern-prothallus. 

 When, of two related groups of organisms, one 

 is decidedly simpler than the other, there is a 

 tendency to assume that the simpler group rep- 

 resents the ancestry of the more complex group. 

 Thus many botanists have believed, either that 

 the ancestors of the Fern-group were actually 

 Bryophytes, or that they at least resembled 

 Bryophytes in their life-history. This belief in- 

 volved the theory that the Moss-fruit is an older 

 type of the asexual generation than the Fern- 

 plant, and great efforts have been made to show 

 how the highly organised plant of the vascular 

 Cryptogams might have been evolved by the 

 elaboration of a fruit like that of a Bryophyte. 

 A vast amount of most valuable research has 

 been carried on under the influence of this 

 hypothesis, which has thus played a useful part 

 in science. It is very doubtful, however, whether 

 any light has thus been thrown on the actual 

 course of evolution. 



The fossil record, so far as it goes, by no means 

 supports the theory; the oldest known vascular 

 Cryptogams do not show the slightest approach 

 to a Bryophytic fruit or sporogonium or any- 

 thing of that nature (Sporogonium is the tech- 



