287 



Soc. N.S.W., beginning xx. 596 (1S95) where they prominently used the term " seedling 

 or sucker leaves " was but the printed expression of their regular practice of a number 

 of previous years in the bush and in the herbarium. The terms were used more or less 

 interchangeably by them. 



Later on I used the term " Juvenile leaves " for sucker leaves (and also 

 sometimes for seedling leaves when the context made it plain), but usually to 

 indicate sucker leaves. 



10. Deaue, 1897.— ' Eucalyptus belongs to a natural order in which the leaves 

 are normally opposite. That the ancestral forms of that genus possessed opposite 

 leaves is inferred from the fact of the leaves being so arranged in seedlings; in many 

 species the change to long and alternate leaves only takes place after several years 5 

 growth ; in some species, such as E. melanojfhloia, the opposite character persists 

 throughout life. (This is not the case as regards this particular species, according to 

 subsequent investigations; see pp. 71, 72, Part XII, and later the subject will be dealt 

 with more fully, J.H.M.) 



These facts seem to point to the probability of the pendent, leathery leaves 

 alternately placed being an adaptation to conditions of drought, and in support of this 

 supposition it has been pointed out that where species have failed to produce the 

 vertically hanging leaves, another expedient has made itself apparent, namely, that 

 they have not only become thick and leathery, but protected with a coating of an 

 oily secretion giving them a glaucous appearance." (Henry Deane, Proc. Linn. Soc. 

 N.S.W., xxii, 471, 1897.) 



11. Goebel, 1900.— 



The difference in the configuration of the juvenile leaves, compared with that of the adult ones 

 is frequently due to the fact that they are arrested formations \ .in other words, the development of the 

 es is the same in both juvenile and adult, but in the juvenile the primordium of the leaf is arrested in 

 its development at a certain stage, and therefore the leaf exhibits an evident, often extremely different 

 configuration. This point in the history of development must also be applied to the explanation of the 

 differences between the configuration of those juvenile forms which have already been referred to as 

 tically primitive and the adult forms, inasmuch as the. latter have acquired their different 

 character by passing through a further transformation. 



In many plants reversion of the adult to the juvenile form frequently occurs. . . . The duration 

 of the juvenile form is scarcely less variable than its external configuration, and is frequently dependent 

 upon external factors, especially in lower plants. ('"' Organography/' Part I, p. 115.) 



12. De Candolle, 1903. — Casimir de Candolle, 1903, loc. cit., p. 9. I offer this 

 in translation: the rest of the paper will be found at Part LII, p. 90. 



Eticai is. — It is known that the trunk of this tree frequently produces adventitious 



shoo' he branches and the leaves having the juvenile form so characteristic of this species. The 



a known for a long while. We have seen above (p. 91, Part LII) that it did not escape 



Pasquale. M. liriosi* h» ly quoted an example remarkable for the great height at which an 



adventitious shoot, with juvenile leaves, was produced on one of these trees. 



1 had myself the opportunity of observing many similar cases during a stay at Cannes in 1899. It 

 is not rare to encounter Eucalypts which have had the branches suppressed or have lost them, by means 

 of accidents, and on which the adventitious shoots are produced round the scars. / hare invariably 

 maintah ed that Ike first branches of these shoots, as well as their leaves, have always the juvenile form and 



* C-. A. Briosi. " Intorno all anatomia dclle fogilie dell Eucalyptus globulus La bill. Milano, 1891, p. 3. 



