120 OCCASIONALLY FATAL. 



and found that by brushing it over his arm he produced 

 effects similar to those of Poison Ivy. In fourteen hours 

 his whole arm and hand were much swollen and badly 

 inflamed. The swelling did not go down for ten days, 

 and effects were felt for a month. 



The poison is in the form of a fatty acid, whose exact 

 composition is not yet determined. It is contained in 

 glandular hairs, which cover the surface of stem and 

 leaves. The effect is strongest in the fruiting period. 

 Even at this time, however, many more people are im- 

 mune than in the case of Poison Ivy. 



The Cypripediums are showy plants with brightly 

 coloured flowers. There are three sepals, coloured like 

 the petals. Two of these are usually united beneath a 

 large, sac-like lip (the "slipper" or "moccasin") formed 

 by one of the petals. The other petals stand out at the 

 sides. There are three stamens, one of which is strap- 

 like and sterile. The other two, one on each side, have 

 two-celled anthers with masses of granular pollen. The 

 leaves are many-nerved and plaited, with a sheathing 

 base. 



The following species are mentioned as poisonous: 



The Smaller Yellow Lady-slipper, Cypripedium parvi- 

 florum Sallsb., is a species widely distributed in swampy 

 woods and bogs. Stem six to sixteen inches high ; petals 

 and sepals greenish, suffused with madder purple, one to 

 one and a half inches long. Lip yellow with purplish 

 spots or lines. 



The Large Yellow Lady-slipper, Cypripediiuu piibes- 

 cens Willd., somewhat larger and more hairy than the 

 preceding, with a larger lip less strongly marked with 

 purple; often growing in clusters in low woods or on 

 moist prairie. 



