92 



Since tlien it does not seem to have been noticed by anybody, except, perhaps, by Herr Goebel, 

 who quotes it apropos of a special case of heterophylly. 1 



To my regret this memoir was still unknown to me, when, several years ago, I made my first 

 communication on adventitious buds. 2 The facts that I then put forth I should admit to-day, were only 

 the confirmation of opinions previously set forth by the Italian scholar. It is the same with the analogous 

 observations made by Prof. Bayley Balfour when he was staying on Rodriguez Island. Having been 

 specially struck by the reappearance of juvenile forms on the adventitious shoots of certain shrubs, he 

 devoted the following lines : — 



" The most striking note of variation in the vegetation of the Island, and it is worth attention, 

 consists in the difference of shape and aspect which the leaves of certain species have in the different 

 periods of the growth of the plant. This variation is seen almost solely in trees or shrubs, with the 

 exception, however, of a Composite of small size, Abroianella. In species endowed with this heteromorphism, 

 the young plant produces leaves having, as it were, a degree of development less than those of the leaves 

 of the adult plant, and from the time that the latter reaches this period of its growth, it only produces 

 leaves of the adiilt form. But, if adventitious shoots arise at the base of the trunk, or even higher, below 

 the first branches, the leaves of these shoots always have the juvenile and not the adult form. 



"Further, if young shoots arise from the trunks of mutilated or pruned trees, the latter also bear, 

 as if it were foreseen, the leaves of the juvenile form. An interesting point to clear up wovdd be to 

 determine if shoots arising from a branch treated in the same way would have juvenile or adult leaves, 

 and how far it would thus produce variations in the foliage. It seems to me that there is here a field of 

 interesting observations and experiences of a kind to fix the attention of those who will have opportunity 

 to devote themselves to research of this kind." 



The author then enumerates up to seventeen species of Rodriguez in which he has indicated a very 

 marked heterophylly. 



Moreover, Dr. Balfour has perfectly recognised the distinctive feature of adventitious shoots, and 

 it is a pity that he is content to describe it incidentally in a floristic work in which it had every chance of 

 being lost to morphologists. If Dr. Balfour had himself pursued the study of the question, he would not 

 have been long in finding, quite within his reach, numerous examples of facts similar to those that he 

 had observed so well in Rodriguez Island. That is what has happened to me many times during the last 

 few years, and I am going to review in turn all the species which have been the subject of my observations. 



He then proceeds to give illustrative particulars concerning E. globulus and E viminalis. See 

 pp. 58-9. (C. de Candolle, Archiv. des Sciences Phys. et Nat., xvi (4), p. 50, July, 1903; translation by 

 J.H.M.). 



[Much of this valuably supplements my notes on the relations between the vegetative form and 

 the flowering period, as given at p. 273, Part XLIX.] 



7. RINGBARKING. 



There is a vast field for inquiry into the best methods of destroying tree-growth. 

 It is a matter of everyday knowledge that trees are sacrificed unnecessarily, but, when 

 it is decided what trees are to be destroyed, there is frequently serious trouble owing 

 to the suckering of certain species (or the ground being taken possession of by others 

 whose seeds have been lying dormant in the ground). The result, from whatever cause, 

 is that ground is taken possession of by scrubby growths which have frequently become 

 well nigh impenetrable, and instead of ringbarking having resulted in an increased 

 growth of grass, the reverse has been the case. So diverse are local conditions that it 

 is impossible to prescribe with exactness the time for destroying trees in every district. 



i " Orgauographie der Pflanzen," p. 145 

 - Arch. rfes. Sc. Phys. et Hat t. viii, 1899. 



