‘THE CONQUEST OF THE DRY LAND IgI 
food, shelter, and moisture. They were the 
pioneers for animals, and the simpler plants 
likewise made higher plants possible. 
According to the rock-record, long ages 
passed before land plants began. For while 
there are fossil remains of seaweeds in very 
ancient rocks, there is no definite evidence of 
land plants till millions and millions of years 
had passed. It was not till ages after that 
(early Tertiary) that grass began to cover the 
earth like a garment—an event with far- 
reaching consequences. 
As to the origin of land plants, there are two 
theories. It is possible that very simple plants 
migrated from the sea to the fresh waters, and 
thence to swampy ground; and that a fresh 
start was made there which gradually led to a 
land vegetation. But one of the most thought- 
ful botanists of to-day, Prof. A. H. Church, has 
recently argued that the highly developed shore 
vegetation of seaweeds may have given origin 
to the dry-land plants by gradual transforma- 
tion. There is no doubt that the seaweeds have 
attained great complexity of structure, and it 
may be that instead of representing a gorgeous 
blind alley, they point the way to higher plants. 
If the coast was slowly raised, as it often was, 
