116 



The Canadian P^'ield-Xatt'ralist. 



Vol. XXXV. 



This slab, with its curved surface, may 

 be considered to represent an arc of a 

 circle which, if completed, would have a 

 diameter of 85 feet. In other words, a 

 slab of Trenton limestone 3% inches thick 



and 266 feet in length could in a period 

 of 75 years or less be bent into a circle 

 if subjected to a stress no greater than its 

 own weight. 



THE TREATMENT OF SKIN IRRITATIONS DUE TO POISON IVY. 



Thd excessive heat of last summer, caus- 

 ing profuse activities of the pores of the 

 skin, was to a measure responsible for the 

 large number of cutaneous inflammations 

 produced by poison ivy. Persons who had 

 never before experienced the effects of 

 poison ivy succumbed to attacks this year, 

 and the usual feeling of security by per- 

 sons considering themselves "immune" 

 was largely lost. Observations for a period 

 ' f years lead me to believe tha" no ])erson 

 is permanently immune, unless he succeeds 

 in avoiding contact altogether. On the 

 contrary, people who heretofore were never 

 bothered by the effects of this plant, 

 and who claimed to be quite immune, be- 

 came violently affected when in a state of 

 profuse transpiration. 



The name poison ivy is well known — 

 and scores of harmless plants are carefully 

 avoided by the camper or picnicker. It is 

 remarkable how few people do actually 

 know and recognize the plant. All |iave 

 8ome idea, mainly the wrong one, until 

 they experience the effect on their own 



skin of having come into actual contact. 

 Where there is rocky ground or pure sand 

 beaches bordering woods, where pines and 

 ash grow, there is it necessary to survey 

 the ground for this bane of outdoor life. 

 Remember the three leaves of poison ivy, 

 whieli distinguis^i it readily from the five- 

 leaved Virginia creeper which it resembles. 

 In fall the leaves turn golden brown to 

 bright red and are not infrequently gath- 

 ered for their glory by the unsuspecting. 

 Beware ! Beyond the beauty lurks the beast, 

 and skin inflammations are sure to follow 

 indiscretion. One would expect that people 

 would be familiar with the appearance of 

 sudh irritation, but only those actually 

 affected remember the symptoms ; indeed, 

 often enough poison ivy ras^i is not rec(^- 

 nized by the learned professions. Invar- 

 iably children are the victims. Picking 

 berries, roaming among the brambles, their 

 naked feet covered with harmless minute 

 scratches; their energy excites their spores 

 to increased activity — and from a few 

 hours to a few days after, there appear the 



