292 



of cases, so small that mere descriptions cannot indicate them, 

 or can do so only with great difficulty and with little precision ; 

 detailed figures elucidate the variations better. It is my opinion, 

 that much of the constant dispute as to how far Alpine plants 

 are xerophytic or non-xerophytic in character is a merely verbal 

 difference 'which might have been avoided if the several authors 

 had given sufficient figures (for instance, as many as Bonier 

 or even more, by preference), — instead of the many verbal 

 renderings, of very little characteristic importance or significance, 

 of shades of difference. 



Between the two extremes — submerged aquatic plants and 

 leafless, xerophytic stem-succulents with abundant water-tissue — 

 there is a long graduated series of life-types. It may be stated 

 at once that no Saxifrcuja approaches these two extremes. The 

 habitats of the species differ however fairly widely and therefore 

 the degrees of adaptation are also somewhat variable. The 

 subject may be best viewed by arranging the sections under 

 investigation in a graduated series according to their greater 

 or less xerophytism. Here we may note the very interesting 

 circumstance that species belonging to the same section are 

 fairly uniform in their degree of protection against excessive 

 transpiration: the purely systematic divisions may be extended 

 to include also anatomical and physiological characters. A 

 careful study of the figures shows this fact more completely. 

 The section Porphyrion (in casu S. oppositifolia) is the most 

 xerophytic, then come the others in the following order: — 

 Trachyphijllnm, Euaizonia, Dacttjloides , Nephrophyllum and 

 Boraphila, the two last being almost similar in regard to this 

 feature. 



Lastly, if we wish to formulate the results thus obtained 

 (the fact should, however, be particularly emphasized that they 

 are of less importance than the information which may be 

 gathered from the figures), it may be done as follows: ~ 



(1) Each section has its own complex of structural 



