268 



structure (my italics, J.H.M.), whatever may be the part of the tree from which they have arisen. I saw 

 also at Cannes many old Eucalypts that had been entirely robbed of all their branches, and whose trunks 

 thus mutilated bore, on their tops, an abundant head of adventitious shoots presenting all the juvenile 

 characters. Having written on this subject to the late M. Naudin, then Director of the Villa Thuret, and 

 who had made, as is known, a special study of Eucalypts, I received the following reply from him, which 

 will not be read, I think, without interest: "I am pleased to be able to confirm your observation on 

 Eucalyptus globulus. Every time that this tree has its trunk cut, it produces an abundant tuft of shoots, 

 which has completely returned to the juvenile state; large leaves, opposite, sessile, or almost so, whitish 

 grey, and with a balsamic and penetrating odour ; quite different, in a word, from those of the adult tree, 

 which are alternate, falcate, petiolate, with whitish powder, and little or not at all odorous, at least on 

 being crushed between the fingers. And note that it is not only at the base of the tree, but at all heights 

 of the trunk, wherever one cuts it that this transformation takes place. Even the simple removal of a 

 slightly heavy branch is the starting of a number of branches returned to the juvenile stage. 1 have 

 observed the same thing on Eucalyptus viminalis, which is very ' biform.' See p. 285). Loppings cause 

 the appearance of bunches of branches in the juvenile stage. It seems probable to me that the same 

 modifications would be observed on all the thoroughly ' biform ' Eucalypts. It would be less evident on 

 the ' uniform ' ones. I think I have also seen similar changes in appearance or something the same on 

 other trees." 



13. Musson, 1905. 



The large size of many of the sucker and seedling leaves, as in our Cabbage Cum {E. hcemastoma), 

 with their frequent horizontal position, doubtless points to necessary " protection " afforded to the 

 young growing tree, possibly a " throw-back "' to leaf character at a time when the Gum Trees 

 lived under more favourable conditions here as to rain and sun — to a great rainfall period, when 

 huge marsupials roamed our forests, and much of Central Australia was occupied by sea; when sun heat 

 was less, sand evaporation much less than at present takes place. With such surroundings leaf growth 

 would be larger, leaves would hang horizontally, and there would be no necessity for narrow, drooping 

 leaves. Present variations therefore lead to interesting speculations in this direction (" Hawkesbury 

 Agricultural College Journal," N.S.W., 25th March, 1905, p. 68). 



14. Diels and Pritzel, 1905. — These authors, e.g., Engler's But. Jahrb. xxxv, 438 

 (1905), use the words " folius primariis." Diels, in his " Jugenclformen unci Blutenreife " 

 of the following year, usually speaks of " Jugendform " as applied to Eucalyptus foliage. 



15. Cambage, 1913. 



"' Juvenile leaves. Under the designation of juvenile leaves may be included not only 

 seedling leaves, but also most of those of certain adventitious growths (my italics, J.H.M.) abundantly 

 produced by cutting or wounding parts of the barrel or branches, and which in Australia are 

 popularly known as suckers, and the difference between these leaves and the mature or adult foliage of the 

 same tree is often so great as to convey the impression to one who has not studied the genus that they 

 belong to distinct species. It is remarkable that Eucalypts rarely, if ever, produce true botanical suckers 

 or shoots from the roots, and a careful examination of the young growths which appear around and at some 

 little distance from a standing tree and look like true suckers, results in the discovery that the plants are 

 seedlings. 



Between these stem-shoot and seedling leaves there is a great similarity, and as according to the 

 general biological belief it is in the young forms of both flora and fauna that we may expect to find the 

 greatest resemblance to ancestral types, so we may regard these reversion shoots as of almost equal value 

 with the seedlings for the purpose of studying the ancestral forms of Eucalypts. Although the leaves of 

 these " suckers " when available are of considerable assistance in the identification of many species, they 

 vary within certain limits both in size and shape, possibly in response to differences of climate, and to 

 extremes of nourishment aud poverty. An interesting feature of their form is the degree of dissimilarity 

 between them and the mature leaves. In some instances the difference is slight and in others exceedingly 

 great. Mr. Andrews has already pointed out that the difference is greatest in the highland and coastal 

 region (Journ. Roy. Soc. N.S.W., xliv, 467, 1910). (R. H. Cambage in same Journ, xlvii, 1913.) 



