ITS CONCLUSIONS PLASTIC 13 



others and vary the general result* It will be seen in the discussions 

 which follow how largely this is so in the morphology of plants. 



It may be objected that conclusions which are so plastic are little 

 better than expressions of personal taste, or even of temperament : that 

 the study of Comparative Morphology is therefore calculated to dishearten 

 its votaries, while the non-specialist public, which is compelled to take 

 its information at second hand, will be bewildered, and will conclude 

 that it is useless to pursue a science which shows so little stability. But 

 even where problems are apparently insoluble under circumstances of 

 present knowledge, it is a satisfaction to most minds to entertain an 

 opinion, even if that opinion be of a theoretical nature, and be liable to 

 future modification or ultimate disproof. On the other hand, as regards 

 the actual progress of morphology, those who follow its history with 

 sympathetic care will gain heart when they compare the present position 

 with that of a generation ago. And especially for Botanists it is encouraging 

 to think that it is little more than half a century since the history of the 

 life-cycle of a Fern was first completed by Suminsky. In some sixty years 

 a vast array of kindred facts has been acquired, and a theoretic super- 

 structure is being raised upon them which, though still protean, is gradually 

 acquiring some settled form. Never in its history has the advance of 

 morphological thought been so rapid as at present. But in no field of 

 morphological research has investigation been more amply rewarded than 

 in palaeophytology : the luminous facts derived from fossils are shedding 

 a fresh and a direct light upon obscure problems, such as the origin of 

 the seed-habit, and helping us to locate such difficult groups as the 

 Psilotaceae and Equisetineae. When we regard these rapid advances, and 

 truly estimate the influence they bring to bear in strengthening the positions 

 already indicated by morphological theory, we shall not only .see that this 

 branch of the science is very actively alive, but also that its theorisings 

 are not merely unsubstantial figments of the mind. 



Considerations such as these go far to justify the statement in the 

 present work of a theoretical view of the origin of a Land-Flora. Some 

 may deem the opinions expressed as unduly speculative, but in the first 

 place, they are based upon a wide area of fact, and secondly, as above 

 remarked, comparative m6rphology must necessarily assume a theoretical 

 form under present conditions. We have seen that its conclusions as to 

 descent are at best the result of a balancing of probabilities. As long as 

 this is clearly understood by the reader, and the author abstains from any 

 dogmatic attitude, good should come from any duly reasoned statement, 

 even though, like the present, it may be of a theoretical nature. A working 

 hypothesis, open like others to refutation, is better than no hypothesis 

 at all. This is the position consciously adopted here, for it is believed 

 that the full statement of even a speculative view will stimulate enquiry, 

 which may lead towards its ultimate proof or disproof. 



