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the seaweeds that are rooted to rock or timber present the 
phenomenon in almost the same simplicity, as their roots 
are little more than holdfasts, and assimilation takes place by 
the whole plant-body, so long as its cellular tissue is alive. 
How often at the seashore may we see a mass of Bladder- 
weed ( Facus v esiculosus or serratus) floating in the tideway ; 
on its outer divisions will be found bunches of soft brown wool 
(sp. of Fdocarpi) , or the pretty red tassels of Ceramium 
rubrum ; on these latter again will be found under the micro- 
scope colonies of the commoner Diatoms, Synedra, Cocconeis, 
or Achnanthes ! Yet all these associated plants build up their 
diverse forms from the same sea water. They all agree in 
possessing chlorophyll, though its presence is disguised more 
or less by other colouring matters : by means of their chloro- 
phyll they all agree in decomposing the carbon dioxide present 
in the water, and in setting free oxygen. But, in addition to 
this common function, the Fuel will select atoms of Iodine 
and Bromine, the Diatoms atoms of Silicon, while the Gorallina 
officinalis, growing on the same rock, will accumulate atoms of 
Calcium. Thus is carried on in its simplest form the trans- 
mutation of lifeless matter into nutritious living substance. 
It is unnecessary, and would be tedious, to follow out the 
process in its increasing complexity through the vegetable 
kingdom. Suffice it to say, that in a tree the appropriation 
of carbon is, in the present state of knowledge, supposed to 
be confined to the green chlorophyll-bearing cells of the leaves 
and similar parts, whilst water, with the other elements of 
plant-food dissolved in it, is sucked up by the roots. The 
higher the plant stands in the scale, the greater is the division 
of labour. 
A few words on the actual adjustment of the animal world 
to its food. The plan that we see to have been in fact 
adopted is this ; a large number of vegetable-feeders is kept 
in check by less numerous carnivorous creatures. So it is 
in the case of mammals and birds, in the enormous class of 
insects, in molluscs. In the class Reptilia , one order, that of 
serpents, is purely carnivorous; another, that of turtles, purely 
herbivorous. Other animals, again, subsist on a mixed diet. 
We have some difficulty in observing Fish, but there are 
many reasons for believing that even in their case plants are 
the food of some genera. Although marine Algce are usually 
thought to extend only a mile or so from shore, Diatoms exist 
almost everywhere in the upper strata of the deep sea. Darwin 
and Sir J. D. Hooker observed them in mile-long patches on 
their voyages. More recently, Sir C. Wyville Thomson says that 
Diatoms are found abundantly on the surface, especially when 
