nitus. 133 



ivy to the tops of the loftiest trees. The leaves arc placed 

 alternately, supported on long petioles, and are composed of 

 three dark green, shining leaflets, about three inches long, and 

 one and a half broad. The leaflets an- of an ovate or rhom- 

 boidal form, pointed, strongly veined, smooth on the upper 

 surface, but always more or less downy beneath, at least about 

 the ribs, and sometimes quite covered with down at the back ; 

 their margin entire. The radical leaves, especially in th< 

 downy variety, are often cut and lobed ; the two lateral leaflets 

 are considerably the smallest of the three, and nearly sessile. 

 The flowers are produced in simple axillary racemes, on short 

 peduncles; greenish-white, and dioecious. The calyx is divided 

 into five deep, erect, permanent segments. The petals are five, 

 ovate, pointed, and spreading. The filaments are five, shorter 

 than the corolla, bearing small, roundish anthers. The gcrmen 

 is superior, roundish, supporting a very short style, with 

 three small heart-shaped stigmas. Fruit a round drupe, 

 about as large as a pea, sometimes pubescent, containing 

 a single, roundish, bony seed {Step, and C/tur., Med. Bot. y and 

 others). 



Geographical Distribution.— North America, from Canada 

 to Georgia. 



Parts used in Medicine, and Mode of Preparation. — 



The Leaves, gathered in May. The juice is expressed, and 

 treated similarly to that of all fresh plants. 



Christison has this remark concerning the JR. toxicodendron, 

 which is worthy of attention. " The active part of this plant is 

 extremely volatile, and the tincture of the fresh leaves or an 

 extract of the same ought to be prepared in vacuo" It is also 

 most important to be remembered that the leaves of this plant 

 should always be gathered at night, and never exposed to the 

 rays of the sun. Exposure to light and sun causes them to 

 become almost entirely innocuous. 



Physiological Effects. — On Animals. Orfila (op. cit.) 



made six experiments on dogs with the extract of this plant. 



n 2 



