A work of this character, the preparation of which has now extended over many years, and covers such a wide range, has necessarily caused us to solicit the help of others residing in the various Australian States, and in every instance this assistance has been readily and generously given. Due acknowledgment was made in the first edition, whilst in this, the second edition, we gratefully recognise the help received in various ways from the following:-

To the members of the Scientific Staff:-Mr. M. B. Welch, B.Sc. (Sydney), Economic Botanist, for valuable help by assisting in the reading of proofs, and in other ways, but more particularly do we wish to acknowledge the sectioning of the leaves for their chromatic illustrations, reproduced in this work. Mr. A. R. Penfold, F.C.S., Economic Chemist, for chemical assistance in the later part of these investigations, particularly in connection with piperitol, terpineol, the aromatic aldehydes and cineol estimation. Mr. T. C. Roughley, Economic Zoologist, for the Eudesmol and Australol photographs, and Mr. C. F. Laseron, for collecting the material.

We are also indebted to Mr. G. Beyer, Chief Clerk, for the indexing; and to Messrs. F. R. Rae and H. G. Goy for clerical help.

Also to Messrs. D. Cannon, F. Morrison, A. J. Holloway, and W. H. Austin.

New South Wales:

J. H. Maiden, F.R.S., Government Botanist; Dr. Cuthbert Hall, Parra-matta; Gillard Gordon Ltd., Sydney; A. J. Bedwell, Sydney; R. H. Cambage, F.L.S., Sydney; D. E. Chalker, Hill Top; \Y. T. Farrell, Sydney; C. Gough, Youri; E. McGrath, Youri; R. H. McNeice, Sydney; W. J. Quigg, Wingello; and Mr. Tivey, Kybeen. VICTORIA :

Professor A. J. Ewart, D.Sc, Government Botanist; J. Cronin, Curator, Botanic Gardens, Melbourne; P. R. H. St. John, Botanic Gardens, Melbourne; Messrs. Cuming Smith & Co., Melbourne; W. Russell Grimwade, B.Sc, Melbourne; D. Clark, Officer; and C. W. D'Alton, The Grampians. SOUTH AUSTRALIA :

Walter Gill, F.L.S., Conservator of Forests; Officers of the Education Department; and E. Burgess, Kangaroo Island. WEST AUSTRALIA :

C. E. Lane-Poole, Conservator of Forests; and W. B. Hooper of the Agricultural Department. QUEENSLAND:

The late P. McMahon, Director of Forests; F. D. Ferguson, Gladstone; the late T. Ingham, Brisbane; J. L. Adams, Cooktown; and H. S. Owbridge, Boyne River. TASMANIA :

L. G. Irby, Conservator of Forests; L. Rodvvay, Government Botanist; and A. H. Higgs.

We also wish to express our thankfulness to the Government Printer, Mr. W. A. Gullick, and the members of his staff for valuable help and expert advice during the passage of the work through the press.