[33] 



Part I. 

 By George Norman, M.R.C.S., etc. 



THE older botanists divided the Cryptogams into Thallogens 

 and Acrogens ; the modern German school requires three 

 divisions : Thallophytes, Muscineae, and Vascular Cryp- 

 togams. In either case, the first division, Thallogens or Thallo- 

 phytes, remains the same, and includes Algae, Fungi, and Lichens. 



The characteristic common to these three groups is the 

 presence of a vegetative body, or Thallus, which exhibits no 

 differentiation into stem, leaf, and root, or, if it does so at all, it is 

 only in a very rudimentary degree. 



Without entering into the disputed question of the position 

 the Lichens should assume in this division, we may say, speaking 

 generally, that the Alg^ and Fungi form by far the largest and 

 most important section. 



About the beginning of this century, little was known about 

 either group, plants being frequently referred to the one which 

 really belonged to the other, and even in the full light of modern 

 investigation there are still genera whose position is extremely 

 doubtfal. One point has, however, been brought out by modern 

 investigation, and that is, the slight difference that exists between 

 these groups from a morphological point of view. In conse- 

 quence, an attempt has been made to arrange Algae and Fungi 

 together in classes according to the method of reproduction, but 

 this has been only partially successful owing to our ignorance of 

 the details of the life-history. 



As to the differences that exist between Algae and Fungi, the 

 most striking one to all observers is, the presence of chlorophyll 

 in the AlgEe and its absence amongst Fungi ; and following on 

 this is the difference as to habit and mode of life. The Funsi 

 are adapted to absorb organic carbonaceous nutriment from their 

 surroundings ; if they obtain it from living bodies, we have 

 parasitism in its various forms ; if they have the capacity of 

 consuming dead organic remains, their habit of life must vary 

 accordingly. 



VOL. v. D 



