BY A. A. HAMILTON. 165 



"There is infinite variation here." In a reference to "Hybrid- 

 ism in the Genus," the author (loc. cit.) refers to a personal ex- 

 perience in a Eucalyptus-plantation in Algeria, where interme- 

 diate forms of planted species, displaying pronounced, morpho- 

 logical characters, were obtained from spontaneous seedling trees. 

 Variation of leaf-characters within, and resemblance without a 

 species, is recorded by Messrs. Baker and Smith (2). E. dextro- 

 pinea R. T. Baker, is noted(p.38) to have leaves almost identical 

 with those of E. Uevoplnea (of this work), and resembling also 

 those of E. ohiiqua L'Her.; and(p.41) E. Icevopinea " sucker-leaves 



alternate or rarely opposite mature leaves varying in size 



and shape, petiole varying from ^ inch to 1 inch long." Mr. R. 

 H. Cambage has devoted a considerable portion of his Presi- 

 dential Address (6) to an exhaustive summary of the morpho- 

 logical characters of the leaves of Eucalypts, showing extensive 

 variation brought about by the necessity for modifications of 

 structure, position, and other characters, to enable them to meet 

 the varying requirements occasioned by the conditions of soil, 

 climate, and other ecological and xerophytic factors, affecting 

 the functional organisms of the members of this difficult genus, in 

 their varied habitats. This writer has also drawn attention to 

 similarity in the texture of the leaves of E. stricta and E. viridis 

 (5 ; 1900, p 602), and {I.e. p. 203) great similarity in the leaves of 

 E. dumosa and E. oleosa Further references bearing on this 

 subject will be found in a series of botanical papers by Mr. Cam- 

 bage (5). The question of hybridism in Eucalypts has been exhaust- 

 ively treated in (18) and other publications by Mr. Maiden, and 

 other specialists in the genus; and the evidence adduced contains 

 examples of similarity in the leaves of apparently distinct species 

 brought about (presumably) by this agency. The similarity in 

 foliage resultant from xerophytic conditions in the small-leaved 

 group of the Myrtacete, is well exemplified in the allied genera, 

 Micromyrtus and Bmckea, the diminutive, triquetrous, more or less 

 decussate leaves of M. microphylla Benth., being, with difficulty, 

 separated from those of B. brevi/olia DC. Succulence, due to a 

 halophilous environment, has enlarged the leaves ef Bceckea 

 crenulata R.Br., when growing on the coast or saline estuary, to 



