68 INTRODUCTION TO CRYPTOGAMIC BOTANY. 



and many of those Cryptogams which are most capable of 

 enduring drought, as Lichens, are precisely those into whose 

 composition a larger proportion of amylaceous matter enters. 

 The spores, too, of some, as of certain species of moulds, are 

 capable of resisting the temperature of boiling water, a fact 

 which would be almost incredible, were it not confirmed by 

 repeated observation. It is true that some seeds of Phceno- 

 gams may be immersed in boiling water without losing their 

 power of germination, but these are seeds with thick integu- 

 ments, through which the heat does not penetrate with suffi- 

 cient rapidity to make a short immersion fatal. I have, myself, 

 recorded an instance of the germination of thousands of grape 

 seeds after three immersions in boiling water ; and Dr. Lindley 

 mentions the curious fact of raspberry seeds growing after being 

 boiled for jam, in which case, if the sugar were really boiling, 

 the temperature would be above the boiling point of water. 

 It is manifest that in neither case were the observations 

 sufficiently exact, as, indeed, too often happens where they 

 are not founded on direct experiment. 



55. Cryptogamic plants are divided naturally into two great 

 classes, viz., those which approximate more nearly, by reason 

 of their foliaceous appendages and green tint, passing into 

 shades of red or purple, to Phsenogams, and which exhibit 

 something more or less remotely resembling the formation of 

 the embryo in Phsenogams, as Ferns, Mosses, Liverworts, &c. ; 

 and those which are leafless, very rarely of a vegetable green, 

 and whose fructification consists either of cells separated from 

 the tip of certain privileged filaments, or formed within their 

 cavity from the protoplasm, which are at once fertile, without 

 any approach to the production of an embryo. The latter, as 

 more simple, will claim attention first. Indeed, the differences 

 between these two great chvisions are so prominent, that the 

 doubt, perhaps, is whether they should be associated under one 

 name, for they are as distinct from each other, as the former are 

 from Phaenogams, to many of whose attributes they approach 

 in Clubmosses, and Marsileacew. Many names have been 

 proposed, to distinguish them, and of these, as the least liable 

 to objection, I shall take those of Acrogens and Thallogens, 

 proposed by Lindley, in the Vegetable kingdom, which are, in 



