ORIGIN OF THE FREE-LIVING STATE 253 



Selaginella, parts which are neither true roots nor axes, but serve as bases 

 of attachment for roots. Though these bodies do not as yet greatly help 

 to solve the question of origin of the root, they draw attention to the 

 Lycopodiales in connection with any discussion how a subterranean 

 absorptive system originated. In the vast majority of Vascular Plants the 

 root is formed early, and is ready as soon as the embryo projects from 

 the prothallus, to take up its physiological duty. There seems in them 

 no need to assume that they achieved their independence through an 

 intermediate " protocorm " stage. It is quite as probable that the transition 

 was in descent, as it is to-day, directly to the rooted state. 



The general conception of the rise of the sporophyte embodied in the 

 preceding chapters differs in its tone and tendency from some of the writings 

 which have preceded it. The attempt has here been made to treat the 

 sporophyte consistently throughout : to apply the same point of view to 

 the Vascular Plants as to the Bryophytes. One important difference 

 between the morphological method adopted here and that of some other 

 writers is that it gives a less prominent place to hypotheses involving 

 reduction from a more complex ancestry. The general principle here 

 has been to assume that morphological characters are in the up-grade of 

 development, unless there is good reason for holding a contrary opinion ; 

 and only to admit that an organ has been reduced from some more 

 elaborate body when there is some assignable reason (comparative or 

 physiological, but preferably both) for that conclusion (Chapter XIX.). 

 A theory of reduction has never been resorted to merely as a means 

 of resolving a difficulty of comparison. The position adopted has accord- 

 ingly been to regard it as probable that the smaller-leaved types were 

 themselves primitive as a rule, though in some there is evidence of 

 probable reduction ; and to contemplate it as probable that microphyllous 

 have given rise to megaphyllous types. It is highly probable, on the 

 other hand, that reduction of size and complexity has been highly effective 

 in certain phyletic lines : for instance, the recognised evolutionary story 

 of the Cycads involves extensive reduction of the sporophylls. l!ut for 

 the primitive strobiloid forms, it would seem to harmonise better with 

 their early occurrence, and their morphological characters, to hold that 

 they represent a relatively primitive condition, rather than a down-grade 

 of morphological complexity. 



The recent changes of view have been in great measure due to the 

 extension of the knowledge of the fossils, both stratigraphically and 

 morphologically. It is true that such data are seldom decisive on ques- 

 tions of comparison (Chapter XVIII.), but the case here is a strong one. 

 It is found that strobiloid forms are at least as early in occurrence as 

 large-leaved Fern-like types. Further, they appear not only to have been 

 present in the earliest fossil-bearing strata, but also well represented in 

 numbers and in variety of type. This has brought with it the conviction 

 that the strobiloid type has quite an equal right with any other to be 



