190 THE PLAKT WOELD, 



Dr. MacDougiirs experiments upon both liimself and others 

 are interesting as well as convincing. Briefly stated, he found 

 that the poison is contained in the small gland-tipped hairs so 

 abundant on the stem and other parts of the plant. About the 

 same percentage of those subjecting themselves to these experi- 

 ments were found susceptible to the poison as were also suscep- 

 tible to ivy poison. The secretion was found to be an acid sub- 

 stance of an oily character soluble in alcohol and increasing, as 

 did also its toxic effects, up to the time of the formation of the 

 seed capsules. 



On May 25, 1907, the Botanical Society of Western Penn- 

 sylvania held one of its field meetings at Hillside Station, on the 

 slope of Chestnut Ridge, in northern Westmoreland County, 

 Pennsylvania, and during the day several fine colonies of the 

 Large Yellow Ladies* Slipj)er.. Cypripediinn hirsiduni Miller, 

 were found along the crest of the ridge. 



Several of the members of the party having expressed sur- 

 prise, not unmingled with doubt, upon the w^riter's statements 

 as to the poisonous qualities of the plant, he determined to put 

 the matter to a personal test. While placing a specimen in press 

 the next morning the middle and lower parts of the stem were 

 lightly rubbed across the inner side of the fore-arm midway be- 

 tween the hand and elbow. Iso effects were to be seen until the 

 third day of the experiment, w'hen the skin began to burn and 

 itch almost exactly as in ivy poisoning, of which the writer is a 

 frequent victim. At the same time the skin became reddened 

 and on the fourth day minute watery vescicles began to appear, 

 increasing in number and in height until about the ninth day. 

 The inflammation was permitted to run its course unhindered 

 and, decreasing after the ninth day, it has at the present writing 

 practically disappeared. The palms of the hands were evidently 

 immune to the poison, as no precautions were taken to protect 

 them while collecting or pressing the specimens and, so far as 

 learned, none of the other members of the party who touched the 

 plants were affected. 



