INTRODUCTION TO CRYPTOGAMIC BOTANY. 29 



studied by competent persons, possessed of an accurate know- 

 ledge of species, much less of a power of appreciating the 

 changes which may take place in the same species, according 

 to varying outward circumstances. Those who have recorded 

 their occurrence, or have given figures illustrative of their 

 aspect and stnicture, accompanied by distinctive characters, 

 have often been physicians better versed in anatomy and 

 microscopy than in cryptogamic botany, and often unable 

 to distinguish a mould from an Alga. The parasites of the 

 vegetable world are much more numerous, and are clearly 

 autonomous; and as some of them produce great ravages on 

 those plants which most subserve the use of man, their study is 

 of immense economical value, apart from other less utilitarian 

 considerations. Till these parasites are accurately distiaguished 

 from each other, all attempts at remedy must be empirical ; 

 and thus, in the case of the diseases which affect the hop, no 

 efficient remedy was even attempted till the natmre of the 

 two principal diseases with which the plant is affected, known 

 under a multitude of names, was accurately ascertained.* 



18. No student of these lower vegetables, then, need blush 

 for his choice. His wisdom plainly is not to confine his 

 views within a narrow prescribed Hmit, and above aU, not to 

 the mere study of species, though that alone is far more im- 

 perative than numbers of pseudo-physiologists will allow. 

 Without it, the results of his observations can scarcely be 

 conveyed with certainty to others, and their field will be 

 greatly circumscribed. The study of species ia itself is of great 

 utility, if conducted on broad and sensible grounds. If he takes 

 a wide view of things, he will be sure in the course of his investi- 

 gation to throw much light even on points which, perhaps, in the 

 first instance, he might least thiak of being able to illustrate. 



19. Nor will a few words on this subject of species be com- 

 pletely out of place, though we have incidentally touched on 

 it before. It is one which the cryptogamic student will meet 

 with at every turn. It is a common opinion that cryptogamic 

 species are so variable, that it is impossible to circumscribe 

 them with specific characters; and, to be studied with certainty, 



* Berk, in Gard. Chron. 1849, p. 467. 



