46 ANCIENT PLANTS 



age conclusion from the study of the details of all their 

 parts. This, however, is beset with difficulties, and in 

 most cases the scientist, weighed by personal inclina- 

 tions, arbitrarily decides on one or other character to 

 which he pays much attention as a criterion, while 

 another scientist tends to lay stress on different char- 

 acters which may point in another direction. 



In no group is this better illustrated than among the 

 Coniferae, where the relative arrangement of the different 

 families included in it is still very uncertain, and where 

 the observations of different workers, each dealing mainly 

 with different characters in the plants, tend to contradict 

 ^ach other. 



This, however, as a byword. Notwithstanding these 

 difficulties, which it would be unfair to ignore, the main 

 scheme of evolution stands out clearly before the scientist 

 of to-day, and his views are largely supported by many 

 important facts from both fossil and living plants. 



Very strong evidence points to the conclusion that 

 the most primitive plants of early time were, like the 

 simplest plants of to-day, water dwellers. Whether in 

 fresh water or the sea is an undecided point, though 

 opinion seems to incline in general to the view that the 

 sea was the first home of plant life. It can, however, 

 be equally well, and perhaps even more successfully 

 argued, that the freshwater lakes and streams were the 

 homes of the first families from which the higher plants 

 have gradually been evolved. 



For this there is no direct evidence in the rocks, for 

 the minute forms of the single soft cells assumed by the 

 most primitive types were just such as one could not 

 expect to be successfully fossilized. Hence the earliest 

 stages must be deduced from a comparative study of the 

 simplest plants now living. Fortunately there is much 

 material for this in the numerous waters of the earth, 

 where swarms of minute types in many stages of com- 

 plexity are to be found. 



The simplest type of plants now living, which ap- 



