AS AIDS IN THE DETEKMINATION OF SPECIES. 3 



In the masterly monograph on the Eucalypts of Austraha and adjoining ishTnds, 

 the " Eucalyptographia," by Baron von Mueller, there are numerous references to 

 the anatomic structure, both of the wood and the leaf-blade, although none of them 

 are concerned with the petiole. In one instance (Decade 7) he has given transverse 

 sections of Eucalyptus wood, accompanied by the remark : — " These microscopic 

 sections are given to aid in the discrimination of mercantile Eucalyptus timber of 

 doubtful origin, such as sometimes occurs in the trade," Here we have a distinct 

 recognition of the idea, and a practical expression of it, that the minute structure 

 of the wood may be useful in determining species, and be serviceable from the 

 timber merchant's point of view. Similarly in the wood-pattern of the leaf-stalk, 

 there are serviceable characters for the same purpose. 



It may be noted here that the existence of such a work as the " Eucalypto- 

 graphia " invests the present investigation with a special importance. There the 

 different species of Eucalypts are fully described and carefully drawn, and we have 

 the advantage of working out a genus from which we can select numerous well- 

 defined species. 



The species selected on the present occasion are such as were conveniently 

 obtainable from the Melbourne Botanic Gardens. Our best thanks are due to Mr. 

 Guilfoyle, F.L.S., Director of the Gardens, for kindly supplying us with fresh 

 specimens when required. Thirteen of these are Victorian, and as there are 38 

 altogether, according to the "Key to the System of Victorian Plants," we hope to 

 deal with the remainder in a future paper. 



We are also much indebted to J. Bosisto, Esq., C.M.G., for supplying us with 

 the leaves of some of the oil-yielding species from their native habitats, and for 

 information contained in various papers read at different times before learned 

 societies. 



Above all, we have to thank Baron von Mueller for verifying each of the 

 species used in this investigation, and thereby enhancing the value of the work — 

 the determination coming from such an undoubted authority on this special group 

 of plants. 



The type sections were prepared and the photographs taken by Mr. Remfry. 



Since the work has been in hand for over four years (the first sections having 

 been cut about September, 1885), it has been possible to show the structure of 

 the leaf-stalk at different seasons, and even in different years ; and, as over a 

 thousand sections have been made, a fair idea of the incidental variation is likewise 



