6 INTRODUCTION TO CRYPTOGAMIC BOTANY. 



if his steps be turned to tropical forests, or to certain localities 

 verging on the extremities of the temperate zones, he will 

 find fungi in Rafflesia, and much more in the whole tribe 

 of ^Balanophoras. In every case, however, alike, he will 

 be deceived by mere analogies, and the deception, with 

 tery rare exceptions, will tend towards the confusion of 

 the lower Phasnogams with the great class in question. It 

 is to this class, long known under the name of Cryptogams, 

 that our attention is to be directed in the present treatise. 



3. The different parts of nature are so intimately bound 

 together, and such unexpected resemblances occur every now 

 and then, as if for the very purpose of arresting man for a 

 moment in his investigations, and prevent him from supposing 

 arrogantly that he can " find out the Almighty to perfection ;" 

 that it is impossible to give exact definitions like those which 

 occur in pure science, which, without a single exception, shall 

 separate with strict accuracy any one division, great or small, 

 from another. The difficulty is just as great when in exten- 

 sive and truly natural genera it is desired to separate one 

 species from another,* as when the objects of separation and 



* Botanists are not in general aware to what an extent this fact is 

 exhibited in the vegetable kingdom, because for the most part they have 

 only very imperfect materials, and therefore suppose that the distinc- 

 tions between species are far more definite than they really are. In a 

 large hei-barium like that of Sir W. J. Hooker, in which specimens 

 exist from every part of the world where a species may chance to grow, 

 the truth of this remark will at once be apparent ; and the veriest hair- 

 splitter will pause before he inflicts on science a multitude of names 

 which can lead to no useful result, but, on the contrary, make botany 

 a trackless wilderness. Dr. Hooker, who has perhaps had better oppor- 

 tunities of realising this fact than any other botanist, has informed me 

 more than once, that he was himself utterly unaware of the full extent 

 of this difficulty before he undertook the preparation of the Flora Indica 

 with Dr. Thomson. Not a single large genus which passed through 

 their hands but exhibited the same difficulty, and in many smaller 

 genera — take for example Tetrather.a, Sm., as lately illustrated in the 

 Flora of Tasmania — the task of ascertaining what are really species is 

 scarcely less perplexing. In treating of ferns, we shall have especial 

 occasion to call attention to this point. The Carices perhaps, as Dr. 

 Hooker remarks, present the most definite characters, but even amongst 

 these, the limits of species are not always very easily ascertained. 



