V 



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6. ADVENTITIOUS SHOOTS. 



Let us now give consideration to two intensely practical Australian questions, 

 more or less intertwined : — 



1. Ringbarking. 



2. Control of Coppice or second-growth. 



Under certain circumstances we wish to destroy trees, large or small, and the 

 methods (other than those of the forester) are ringbarking for trees of large, medium, 

 or even small size, and the use of the axe or tomahawk and the mattock for saplings. 

 As the work is usually done, there is always more or less risk of suckers, resulting through 

 imperfect ringbarking, or because of imperfect grubbing. 



I preface notes on ringbarking and coppicing by offering translations of two 

 interesting articles, by Planchon and Casimir de Candolle, written many years ago. 

 The physiology of Eucalyptus trees, then recently introduced into Europe, presented 

 very great scientific interest to these eminent botanists. The latter quotes earlier 

 papers bearing on the same subject, and these references are important. 



Planchon, 1875.' — The Eucalyptus globulus presents itself under two very striking aspects : the 

 infantile form, in which the leaves are opposed and sessile; that is, a sort of larval state, during which 

 the plant is not apt to flower ; and the adult state, in which the leaves are alternate and petiolate, and 

 which is the perfect state, characterised by the presence of fruit and flowers. 



It is not necessary to resort to analogies, and to compare this dimorphism of the Eucalyptus to 

 those metamorphoses- that insects undergo; such, for example, as the changes of the same insect through 

 the forms of caterpillar, chrysalis, and butterfly. Iu the latter case, it is the individual itself that throws 

 off its successive envelopes, and appears with new forms, resulting from internal effort and changes of the 

 same organs. Iu the case of the Eucalyptus, it undergoes no metamorphosis, but only appears with new 

 organs superadded to the old ones ; or, more properly speaking, the tree represents, not an individual, 

 but a foliate collection (the phytons of Gaudichaud), each successive element having its own form inde- 

 pendent of the form of the elements which precede and follow it. The resemblances or the differences 

 of these elements do not alter its own individuality. In short, it is a successive polymorphism, and not a 

 metamorphosis in the primitive sense of the word. 



This polymorphism is not, however, a general character of the Eucalyptus. It is in a certain measure 

 wanting in the species Eucalyptus cordata, which flowers upon branches with opposed leaves. (An isoblastic 

 species, J.H.M.) Here the adult and infantile states are confounded; and without attempting to establish 

 a too narrow assimilation between animals with centralised functions and plants with multiplied 

 elements, it is, perhaps, allowable to compare the infantile and adult forms of the dimorphous Eucalyptus 

 to the two states of tadpole and adult of common batrachians (toads, salamanders) ; whilst the 

 Eucalyptus fructifies upon its branches an infantile type which may be analogus to batrachians called 

 Perennibranchee, which reproduce themselves while preserving the character of larvae to the branchial 

 respiration. Whatever may be the character of this general assimilation, the prominent fact is the 

 existence of two states of foliation among certain of the Eucalypti, and only one state among (most, 

 J.H.JL) others. Now, from causes the action of which cannot be foreseen, a Eucalyptus of this first 

 group f.uctifies upon its young branches, and the seeds of the fruits may not, in germinating, reproduce 

 the characters of the branches from which they are derived; will not nature have thus formed by a 

 simple variation of fixed foliage nearly the equivalent of that which is always described as the species? 

 In other words, if we find the habitually sterile branches of a Eucalyptus globulus normally fructifying, 

 have we not before us a new form of the type, which, encountered by itself and disconnected with 

 its point of departure, would naturally be described as the veritable species? And what assurance have 

 E 



