FOSSIL ALG^E. 



THERE cannot but be general agreement in the view 

 that all theories of the evolution of plant forms must 

 be based on the assumption that Algae are among the least 

 changed descendants of the earliest forms of life on the 

 globe. They represent an extreme term in the series of 

 autonomous organisms capable of converting inorganic 

 matter into food substance, and though organisms of more 

 simple organisation are known, these are parasitic or sapro- 

 phytic and accordingly may be, must be, accounted for on 

 the same theory, as derived by degeneration from forms 

 such as Algae vegetating by their own intrinsic chlorophyll, 

 using the word in its widest sense. Since successive re- 

 searches of absorbing interest made during recent years 

 have declared an express complexity of cell-organisation 

 even in the simplest forms of Algae we may further proceed 

 to assume without violence the possibility of the existence 

 even now, or, at all events, in past ages, of still more element- 

 ary organisms of like autonomous character represent- 

 ing a more remote ancestral type. However far back 

 we may push such speculative conceptions of element- 

 ary organisms it is plain that whether they did or 

 did not exist in past ages, their bodies must have been 

 so little specialised in the direction of stable structures 

 that we cannot hope for their preservation in fossil forms. 

 The student of the primordial forms of life must therefore 

 content himself with fossil Algae as the representatives of 

 the earliest type, and he is driven to this by another con- 

 sideration. It is of course conceivable that more primitive 

 organisations than these should occur in fossil form, but 

 from the nature of things we should not be justified in 

 assigning them to the main series of independently vegetat- 

 ing organisms, since, as has been said, we already know 

 simpler forms of degenerate type with which they might be 

 classed with equal propriety so far as the remains of cell- 

 walls, etc., could guide us. 



