Long 1917
PREFACE
As in the case of a previous volume. Common Weeds of the Farm and Garden, the preparation of this handbook was undertaken because of the great lack of readily available and rehable information on the subject in Enghsh scientific literature. Many of the facts were known to a few interested persons, but many others were so scattered here and there in technical reports and journals that they were scarcely known even to expert chemists and botanists. The bringing of this information together in some sort of order has involved considerable labour extending over several years, but if the volume be found helpful to those for whose use it has been prepared I shall feel more than gratified.
That the subject is of importance is fully reahsed by farmers and veterinary surgeons ahke, for the annual loss of stock due to poisonous plants, though not ascertainable, is undoubtedly considerable. It was felt that notes on mechanical injury caused by plants and on the influence of plants on milk might usefully be included, as in some degree related to poisoning; this has therefore been done. On the other hand, a number of cultivated plants {e.g. Rhus, Wistaria) which are poisonous have not been included because exotic and hardly Hkely to be eaten by stock. Fungi generally also find no place in the volume, as they are suflS.ciently extensive" to deserve a volume to themselves, and are far less readily identified than flowering plants.
The dividing Une between plants which are actually poisonous and those which are only suspected is far from clear, but a division was considered desirable for the convenience of the reader, and an endeavour has been made to give a sound but brief statement as to the present information on plants poisonous to live stock in the United Kingdom, with symptoms, toxic principles, and a hst of the more important references to the bibhography in relation to each plant included in Chapters ii to vi (the numbers corresponding with the numbers in the Bibhography).
Regarding symptoms it is to be regretted that in many cases they appear to be the result of injections of the toxic extracts, and not observations made after natural poisoning by ingestion of the plants.
Further, there may frequently be doubt as to the identification of the plant suspected of causing poisoning; indeed, in some cases it is possible that the identification rests on the veterinary surgeon or the stockman thinking a certain plant is the cause. The most complete and systematic account of European poisonous plants is that of Comevin (1887), and references to poisonous plants in the ordinary literature are heavily indebted to him. In so far as the toxic principles of the plants are concerned, however, his book is in many instances no longer reliable.
The chemical formulae, quoted for the use of students and research workers, have been checked by consulting works by the following authors, the reference to the bibliography being given in brackets: Henry (128), Dunstan (76), Allen (4), Haas and Hill (114), Thorpe (240), Van Rijn (252), Robert (161), Esser (81), and Beilstein (16).
Apart from the literature consulted I desire to acknowledge my great indebtedness to the Board of Agriculture and Fisheries for kind permission to make use of official records; to Mr F. W. Garnett, M.R.C.V.S., for kindly reading the proofs from the veterinary standpoint; to very many Experiment Stations, State Departments of Agriculture, and other authorities in Australasia, America and the Continent of Europe, for assistance given and literature sent; to Sir David Prain and members of the staff at Kew for much friendly advice, and aid in consulting the Kew Ubrary; to Sir James Dobbie for permission to spend some time at the Government Laboratories to consult certain volumes; to Mr T. H. Middleton, C.B., Dr E. J. Russell, Professor W. Somerville, Sir Stewart Stockman, Professor T. B. Wood, and others, for information and many helpful suggestions ; to my friend Mr W. A. Whatmough, B.Sc. (Lond.), for many sugges- tions and kindly reading the proofs; and to my colleague Mr W. R. Black for invaluable help in preparing notes, checking data and reading proofs. To all these, and many others who are not mentioned by name, I tender my sincere thanks.
For any shortcomings I crave the indulgence of my readers, only requesting that they be friendly enough to spare a moment to call my attention thereto.
H. C. LONG.
SURBITON, October, 1916.
