TRANSACTIONS OF SKCTION K. 1043 



There are two extreme courses open to tliose wlio wish to convey clearly to 

 others such matters as these ; the oue is to use a separate term for eacli category of 

 parts, which can be followed as maintaining its individual or essential identity 

 tiiroughout a recognised line of descent — in fact, to make a polynomic termi- 

 nology of members run parallel with a polyphyletic development. The other 

 course is to make it clear always in the use of terms applied to parts, that they 

 do not convey any evolutionary meaning, and to use them only in a descriptive 

 sense. Perhaps the former is the ideal method, and it may be a desirable thing, 

 as polyphyletic origins of parts become more established, that the terminology 

 should be brought to reflect at least the more important conclusions arrived at. 

 How this may be done we leave for the future to decide, though I have indicated 

 A first step in the case of the leaves of Mosses and Ferns. 



But, for the present, the whole matter is still so tentative that it is well to 

 be content with something which falls short of the ideal, and to maintain the 

 usual terms, such as stem, leaf, root, hair, sporangium, &c., as simply descrip- 

 tive of parts which correspond as regards general features of origin, position, and 

 nature ; but with no reference either, on the one hand, to conformity to any ideal 

 plan, or, on the other, to any community by descent — in fact, we shall preserve the 

 original pre-Darwinian sense of these words, which was purely descriptive, and 

 avoid any attempt to read into them any accessory meaning. 



A special interest attends those cases of transfer of inherited developmental 

 capability where a part appears with its normal characters, but in a position which 

 is not usual, such as the transfer of the sori of Aspidium cuiomalum ; comparable 

 with these transfers on the one hand are those apogamous growths where roots, 

 leaves, ramenta, sporangia may arise independently out of the usual succession. 

 These may be compared, on the other hand, with those interpolations of extra 

 parts, such as the accessory stipules in the stellate Rubiacese, the extra stamens 

 in Rosaceae, &c. "\Ve are unable as yet to say what it is which determines the 

 position and mode of origin of parts ; I do not myself think that Sachs's hypothesis 

 of ' Stofi' und Form,' involving ideas of material diflferences which have not been 

 demonstrated, will advance the question so much as a careful following of the 

 details in the origin of the parts, say in some of these apogamous growths. 

 Here we see the plant body in a sense analysed before us ; an)' one part may be 

 produced separately from any other. An elucidation of how any one of these is 

 initiated and determined should lead to a knowledge of the influences which act 

 also in the normal sequence, and determine the origin of parts in the plant body at 

 large. 



I have attempted to touch upon some of those questions in the Morphology of 

 Plants which specially interest us at present, and I dare say in doing so have 

 revealed to you some of the special weaknesses of this branch of the science. The 

 want of finality in this unravelling of history without documents, the ample lati- 

 tude for difference of opinion, according to the relative weight attached by one or 

 another to the same facts : these are difliculties inherent in the very nature of our 

 study, while to many minds they increase rather than diminish its attractions. 

 Nevertheless the progress of morphology in late decades has plainly been towards 

 a truer appreciation of how divers forms have originated, and so towards a better 

 recognition of affinities. Seeing that' this is clearly the main trend, we may take 

 heart as to the advancement of morphological knowledge. We shall not allow 

 ourselves to be deterred by reason of the want of finality or the deficiency of 

 evidence, however strongly we may feel the weight of these difficulties. We shall 

 rather try to make the best of such evidence as we possess, with the full confidence 

 tliat, however insoluble the problem of descent may really be, inquiry along 

 scientific lines will at least lead us nearer to the goal. 



The following Report and Papers were read : — 

 1. RejMrt on Fertilisation in Ph3eophycea\ — ,See Reports, p. 729. 



3x2 



