52 INTRODUCTION TO CRYPTOGAMIC BOTANY. 



up in certain vesicles,* after deposition by the male, as in 

 Aphides and Gryllus, there is any indication of higher 

 dignity, though the process is more complicated ; but even 

 granting that the naked ovule may be the less perfect organ, 

 the whole system of vegetation is so entirely different from 

 that of the highest Cryptogam, that I am unable to see a 

 particle of affinity, nor, indeed, in the vegetable world, as at 

 present known, am I able to trace any close connection 

 between Phasnogams and Cryptogams, look which way we 

 may. Both, indeed, are vegetables, and both have certain 

 points of resemblance, and similarity of organs ; but in every- 

 thing which regards essential character they are altogether 

 distinct, as, on the other hand, I am inclined to think is the 

 case with the two great divisions of Endogens and Exogens : 

 there may be some difficulties as to the order of development, 

 but still, in every case, the grand distinctive points remain 

 fixed and certain, and the separation of such plants as Tamus 

 and its allies, under a distinct order, serves only to confound 

 distinctions which appear to me absolute. 



39. One fertile origin, indeed, of such notions as to the close 

 relation of organisms in reahty so widely divided, dejDends on 

 the prevalent idea that there are no such things as definite 

 groups in nature. All, it is said, pass into each other by 

 insensible gradations. It is necessary, however, to have definite 

 notions of the typical characters of families. It is true certain 

 characters miay be common to two groups, but this does not 

 prove affinity. There is a definite distinction between en- 

 dogenous and exogenous growth, between a Monocotyledon 

 and a Dicotyledon, between a Phoenogam and a Cryptogam; and 

 though there may be modifications of these distinctions, yet 

 these modifications often take place at points as far as possible 

 distant from each other; not where endogenous and exogenous 

 plants might be supposed to be confluent. Dictyogens, for 

 instance, are supposed to approach Exogens in their leaves 

 and in the arrangement of their tissues, but their embryo 

 and the development of their wood are as distinctly mono- 



* Lesp6s M6moire sur les S]:>ermatophores des Orillous, Ann. d. Sc. 

 Nat., S6r. 4, v. iii., p. 366. 



