io6 The Ottawa Naturalist. [August 



General conclusions are drawn which indicate that in all 

 the provinces large tracts of untilled land exist that would rank 

 with the fertile soils of other countries and, further, it is shown 

 that many Canadian soils are possessed of most abundant stores 

 of plant food — stores so vast as to allow of their most favourable 

 comparison with the richest soils of which we have any know- 

 ledge. 



THE POISON OF POISON IVY {Rims radicans). 



In the Year Book of the United States Department of 

 Agriculture for 1896, recently issued, there is a very interesting 

 chapter entitled : " Some Common Poisonous Plants," written 

 by Mr. V. K. Chesnut, of the Division of Botany, U. S. Depart- 

 ment of Agriculture. Among the plants described and illu- 

 strated, the Poison Ivy, "as the principal poisonous plant of 

 America," receives attention. After an account of its habitat 

 and botanical characters, in which the writer points out how it 

 may be distinguished from non-poisonous plants that bear cer- 

 tain resemblances to it in the form of their leaves, &c., there 

 follows a discussion regarding the nature of the poisonous 

 principle — a question over which there has been much dispute. 

 As this is a matter of no little interest and practical importance, 

 we shall quote at some length this part of the author's article : 



. '• Poison ivy has long been regarded by the ignorant with 

 a degree of awe akin to superstition. No one was able to tell 

 how it produced its effects, and why it attacked some people 

 and not others. Mysterious principles were relied upon to 

 explain the phenomena, and up to the present time the common 

 belief has been that the poisonous constituent was really an 

 exhalation from the plant. In the latter part of the last century 

 it was so regarded by the expert ; then, as our knowledge of 



