INTRODUCTION TO CRYPTOGAMIC BOTANY. 19 



exclusively to animals. He concludes, therefore, that he must not 

 expect the whole of the definition to answer, and is content if 

 he can find one point at least which leaves him in no doubt. 



10. All these cases were more or less exceptional, but he 

 finds others which present far less difficulty, none perhaps which 

 do not present some, and he soon perceives that there is a com- 

 mon band which binds the whole, however different the parts 

 may be, and, as he gets to subordinate divisions his difficulties 

 rapidly diminish. The number of points of agreement, that 

 is, will increase, while those of difference decrease, though he 

 will scarcely find one production which does not in some par- 

 ticular depart from the terms of any definition which can 

 comprise the whole. Few students would, however, have 

 worked this out for themselves. The confusion would have 

 seemed so inextricable, that they might well have given up 

 the matter in despair, and yet, if the caution be once well 

 understood, that we are not to look for mathematical pre- 

 cision or for characters which can, without failure, include 

 every form in groups manifestly bound by some common tie, 

 there is no more difficulty than would be found in any definition 

 of Phfenogams taken from characters which are not universal. 

 All Cryptogams are reproduced by spores, and all Phrenogams 

 by seed ; in one (as a general rule) there is no embryo, in the 

 other an embryo always exists ; and yet, if germination by 

 means of a protruded filament be the essence of a spore, there 

 are many Cryptogams which will not come under the definition. 

 Meanwhile, however, he will have found interest increase with 

 the examination of the new world to which the microscope has 

 introduced him, and he will not be long before he sees that 

 the interest does not cease with the mere ascertainment of the 

 structures before him, but that a vast field, of physiological 

 wonder is opened to his view. 



11. And here the great importance of Cryptogamic Botany 

 forces itself upon us. It has often, indeed, been objected, 

 that so mvich credit is not to be obtained in the pursuit of this 

 branch of botany as in the investigation of the more highly 

 organised vegetables ; and some of the first Cryptogamists of our 

 day have felt this so strongly, that they have even been in 



