The Evolution of Plants. 5 
Later on the conditions for the evolution en masse into 
land plants of the green highly developed benthon whose 
characters have been indicated were presented by the rise of the 
incipient continental areas above sea level. The land thus 
first exposed was not covered by more or less deep deposits of 
soil, the results of long continued subaerial denudation, but 
consisted of bare rock surfaces, bearing, according to the theory, 
great masses of marine vegetation. Copious precipitation and a 
saturated atmosphere may be reasonably postulated, but the 
supply of nutritive salts, supposed to be present in the 
primeval ocean, would be entirely cut off, unless we postulate a low 
tide-wave with periodic return, or wetting within the range of the 
“ splash.” 1 The emerging surface would however shortly be 
covered with the remains of dead forms which had not survived 
the first stage of the transmigration, and the organic debris so 
produced would form the first (an organic) soil, from which the 
soil as we know it would be evolved by the gradual accumulation 
of the products of subaerial denudation. This organic debris 
would remain saturated in a saturated air, and would furnish the 
substratum from which the transmigrants would have to obtain 
their food. 
And now we come to the weakest part of the author’s 
exposition—'his account of the way in which the vegetative bodies 
of these transmigrants became actually adapted to land life. 
Admitting that his general considerations are sound, and that his 
analysis of the factors is correct, we find no convincing picture of 
the actual transformation. Mr. Church conceives that the various 
types of algal organisation originating in the sea maintained 
their essential characters after the transmigration. Plankton 
forms remained plankton, even if they became “ cryoplankton ” or 
“ dendroplankton ” : filamentous forms remained filamentous ; and 
the more massive parenchymatous forms retained their cellular 
organisation which formed a basis for further adaptation. Thus we 
have the picture of comparatively massive forms capable of standing 
up by themselves (comparable with the Fucaceous Cystoseira) 
having an initial advantage on this account and being able by their 
massive structure to resist desiccation; increasing their deposits of 
“ polysaccharide ” (cellulose) as a result of the greater insolation ; 
1 Here it may pertinently be asked: What is the probability that the 
primeval ocean had anything like the salt content of the sea as we know 
it to-day ? The original ocean must have consisted of water condensed and 
recondensed on the cooling surface of the globe, and thus destitute of salts. 
How and when did it acquire its existing salt content ? 
