preaching the natural conditions as nearly as possible, 

 that final and dependable results can be obtained. A 

 creditable beginning has been made both in the United 

 States and in Canada. Such work along physiological 

 lines should be continued as well as research on the pois- 

 onous plants from the chemical standpoint. This is the 

 immediate need. After proper antidotes and treatment 

 have been discovered, however, there still remain two 

 problems one in connection with the utilization of the 

 highly complex organic products that some of these 

 weeds* contain, products that are very difficult to form 

 synthetically in our chemical laboratories; and the other 

 concerned with the elimination of the weeds themselves 

 from our grain fields, pastures, parks and ranges. The 

 importance of such work to the community at large war 

 rants a comprehensive plan of attack and ample govern- 

 ment support. 



No bibliography has been compiled. This service has 

 been admirably performed in Pammel's "Manual of Pois- 

 onous Plants," and Long's "Plants Poisonous to Live- 

 stock," which should be consulted by everyone wishing to 

 make a more special study of the subject. References to 

 these books and the many publications of the various 

 agricultural departments and colleges will be made 

 throughout the work. 



The authors wish to express their indebtedness to Pro- 

 fessor N. C. Hart, of Western University, and Miss M. V. 

 McCulloch, of the Botany Department, University of 

 Toronto, for contributions to the illustrations, and to 

 Miss Jane McGillicuddy for help in the preparation of the 



*An industrial use has already been found for Wild Mustard, 

 Brassica arvensis, the seed of which is being separated from grain 

 screenings by special machinery and utilized on a commercial scale, 

 at the same time improving the screenings for feeding purposes. 



