FERN CONFERENCE. 



499 



between extremes of greater and less bulk, and the series may 

 be laid down thus : — 



(Relatively bulky.) 



Ophioglossacese. 



Marattiaceae. 



Osmundacea\ 

 ychiza^ace.T. 



(Gleicheniacere ?) 



Polypodiacejc and Cyatheaceae. 

 Hymenophyllacen?. 



(Relatively delicate.) 



This I believe to be a true series, from the evolutionary point 

 of view ; it may be objected that bulk is not always a satisfactory 

 character, and I admit that in detail it is not within narrow 

 circles of affinity. Everyone knows of genera which include both 

 relatively delicate and fleshy forms — e.g. Euphorbia, Senecio ; or 

 it may be pointed out that a single species may vary in this cha- 

 racter according to its position, and I well remember a peculiarly 

 fleshy form of Lychnis dioica growing on the Bass Rock, in ap- 

 pearance quite distinct from the inland plant ; and this is not 

 uncommon in other plants. But the point is, in the case of the 

 series of Ferns, that all the parts show the parallelism, and that 

 it maybe traced in the earliest stages of development. Moreover 

 the series, as above laid out, conforms in the main to the views 

 of botanists, arrived at on purely systematic, as apart from 

 developmental, grounds ; a point which is the strongest possible 

 support to the recognition of the series as a natural one. 



I shall assume, therefore, that it will be granted that the 

 series is a natural one, and we may now proceed to discuss the 

 main question with regard to it, which I propose to bring before 

 you to-day, viz. which is the upper and which is the lower end 

 of the series ; in other words, are these more simple Ilymeno- 

 pliyllaccce the original type of Ferns, or are they a degenerate 

 type? 



In the memoir, published in 1889, in which this series was 

 laid out and discussed (p. 374 ) I concluded that the series from 

 the HymenophyllacccB onwards is an ascending series, though it 

 was remarked that the converse is capable of defence ; since then 

 a paper taking the opposite view has been published by Douglas 

 H. Campbell (Bot. Gaz. January 1890). But since this does 

 not exhaust the discussion I shall now reconsider the pros 

 and cons of these two views ; and first we shall see what may be 



