10 



leaves with impunity. It acts upon the skin of the majority of persons 

 but with varying intensity. Many people are probably wholly immune, 

 but some lose their resistant power in middle life; others have been 

 known to attain immunity from it to a very considerable degree. There 

 is a similar variability in the effects of poisonous plants taken internally. 

 The qualifications involved in a definition of a poisonous plant are 

 numerous, and can not well be introduced into this report. It may 

 suffice here to say that death in some cases is attributable not to any 

 poison which the plant contains, but to immoderate or incautious eating, 

 or to mechanical injury, such as is produced in horses by the hairs of 

 crimson clover, which under certain conditions accumulate in large balls 

 and obstruct the intestines, or to the effect of parasitic growths, such 

 as ergot occurring on rye. Neither the clover nor the rye is poisonous. 



Excluding all which operate in these ways, there is, however, a large 

 number of really poisonous plants whose properties are comparatively 

 unknown. Information relating to them is obtainable only from the 

 most diverse sources. Cases of poisoning are described in medical 

 journals, communicated by farmers, or simply alluded to in newspapers, 

 and are traceable only through correspondence or personal inspection. 

 Records of chemical analyses and toxicologic^! experiments are scat- 

 tered through all kinds of literature. Additional reason for the preva- 

 lent ignorance in regard to these plants is to be found sometimes in 

 their limited geographical range, and sometimes in the uncertainty and 

 often opposite results obtained by unscientific experiments. 



In this bulletin it has been found impossible to give an adequate 

 treatment of all of our poisonous plants. Those cultivated in gardens, 

 such as the oleander (Nerium oleander), mezereon {Daphne mezereum), 

 foxglove (Digitalis purpurea), and the species of Xarcissus, have been 

 omitted, as have those wild plants whose poisonous qualities have not 

 been investigated at some length. In the latter category are the cock- 

 leburs (Xanthium spinosum, X. strumarium, and X. canadense), sleepy 

 grass (Stipa viridula robusta), elder (Sambncus canadensis), pimpernel 

 (Anagallis arrensis), and Labrador tea (Ledum groenlandicum). The 

 limit of space has precluded a more extended treatment of many species, 

 and cut out altogether many of the fleshy and all of the parasitic 

 fungi. 



The matter presented in this bulletin has been obtained in part from 

 published articles or treatises, but most of it has not heretofore been 

 printed. Besides the direct information secured through correspond- 

 ence with medical men, scientists, farmers, and others interested in 

 cases of poisoning, considerable information has been obtained from 

 personal observation and experiment. The writer has had constant 

 recourse to the valuable treatises of Cornevin, Blyth, Kobert, Dam- 

 mann, Millspaugh, White, and Van Hasselt; to the numerous articles 

 found in the various botanical and chemical journals ; and to the medical 

 literature indexed in the invaluable catalogue and Index Medicus of 



