67 



Hybridism in the genus. — The most convincing illustrations of hybridism in Eucalyptus (which 

 is not Very obvious as a rule, and hence has been denied), to me personally were afforded by a Eucalyptus 

 plantation in Algeria, where intermediate forms of planted species displaying pronounced morphological 

 characters were obtained from spontaneous seedling trees. We rarely cultivate Eucalypts in Australia 

 on a large scale, and some of the exceptions are the plantations at Wirrabara and other places under the 

 direction of the Conservator of Forests of South Australia, Study of these plantations would doubtless 

 afford valuable data in regard to the evolution of new forms. 



Hybridisation in wild species has apparently not been much investigated in any part of the world 1 . 

 As regards Eucalyptus I have brought together a considerable number' of facts 2 bearing on the subject, 

 and have referred to the matter from time to time in my " Critical Kevisfem of the genus Eucalyptus," 

 and other works. As in Australia the evidence a-s to Eucalyptus hybrid.s is,,ruainly based on inference, 

 it appeared to me best, when I shall have cleared the ground by a critical examination of each species, to 

 devote some parts of that work to consideration of the question of hybridisation atone, since, in my view, 

 pictorial illustration is necessary to a proper understanding of it. v , ' , 



I am redeeming my promise in the present and following Part. > wwO) ■-.-. 



Perez, 1919 et ante. — The late Dr. G. V. Perez was for a number of years a firm 

 believer in hybridisation in the genus. See under E. ficifolia x calophylla at p. 281, 

 Part XLIX of the present work. ; 



Baker and Smith, 1920. — In " Research on the Eucalypts," 2nd edition, p. 13, 

 there is a note headed '"'Hybridisation." On reading this page-; it is difficult to 

 understand whether Mr. Baker believes that hybridisation occurs in the genus under 

 natural conditions. At all events, the admission, if made, is done very grudgingly. 

 I do not complain of the exercise of caution in the matter, for, as a botanist who has 

 perhaps given more attention to the subject than any other Australian worker, I freely 

 admit that the subject is full of pitfalls, which particularly beset those who have not 

 endeavoured to view it from every direction that presents itself. At the same time 

 much evidence has been available for a good many years now. 



B.— BIRDS AND FERTILISATION. 



Here is an appropriate place to refer to the remarks of A. G. Hamilton, one of 

 the most distinguished of Australian workers on fertilisation. I quote from two of his 

 presidential addresses before the Linnean Society of New South Wales, as contained in 

 the Journals of the Society. The whole of the addresses should be read. 



Little that is definite is on record about the pollination of Eucalyptus, or, with one exception, of 

 Acacia. I looked up both orders in Hermann Midler's and Knuth's books, and was greatly astonished to 

 find that neither book has any reference at all to the Myrtaceae. The order seems to have been passed 

 over by inquirers into pollination methods. And very few observations are recorded on Acacia. In the 

 case of Eucalyptus, we know that the flowers aie visited by the brush-tongued lories and by some of the 

 honey-eaters. In a paper by Mr. Swinnerton " On Short Cuts by Birds to Nectaries " (Journ. Linn. Soc. 

 (Bot.), vol. xliii), being observations made in South Africa, he mentions E. ficifolia as being visited by 

 Sunbirds, and also by other birds, as well as insects. He believes that in South Africa this species is chiefly 



1 "Hybridisation of Wild Plants." D. T. MacDougal, Bot. Oaz. xliii, 45 (1907). 



2 "On Hybridisation in the genus Eucalyptus," Proc. Aunt. Ass. Adv. Science x, 297 (1904) ; Proc. Linn. Soc, 



N.S. W., xxx, 492 (1905) ; Pro. Boy. Soc, N.S. W., xlvii, 233, (1913). 



