u 



a volatile alkaloid, the other, John M. MalBch, denied it, stating 

 that volatile acid, which he called " toxicodendric acid," is the 

 active principle. 



Both statements proved to be erroneous, as experiments which 

 I made a few years ago have shown. 



The lack of any rational treatment of ivy poisoning may 

 be ascribed to the imperfect knowledge of the cause of this 



In my researches (Journal of Exjjer. Med., Vol. II., No. ii,, 

 p. 97) I used different parts of the plants, gathered at different 

 seasons of the year, and found that the so-called " toxicodendric 

 acid," which Maisch did not produce in the chemically pure state, 

 is nothing but acetic acid, and, therefore, not the cause of the 

 eruption peculiar to ivy poisoning. 



Further investigations showed that the active principle is an oil, 

 which I named " Toxicodendrol," and which can be found in all 

 parts of the plants, both in Rhus Toxicodendron and Hhus 

 venenata. This oil is easily soluble in alcohol, ether, chloroform, 

 &c., but is insoluble in water. Toxicodendrol is easily decom- 

 posed by heat, but very slowly at ordinary temperatures. A 

 sample of it, which had been kept in an open porcelain dish for 

 over 13 months, was partly converted into resin, but the remaining 

 oil proved to be just as active as before. The active oil was also 

 prepared from plants collected during the winter, after having 

 been covered with snow for weeks, and from dry stems and 

 branches which had been kept in the laboratory for over a year. 



To test the strength of the "Toxicodendrol," I made many 

 experiments and found the oil active in the minutest quantities ; 

 in one case as little as -pjV^ mg. of the oil dissolved in 2 drops of 

 olive oil proved effective. 



The time of incubation varied from 18 hours to 9 days. This 

 long period of incubation and the stability of the oil explain the 

 belief that direct contact is not necessary to contract the disease. 

 When the first symptoms appear, several days have usually passed, 

 and a person may then not remember having come in contact 

 with the plant. On the other hand, some of the oil may stick to 

 the clothing, &c,, and this may cause the disease even after several 

 months have passed. Jn making these experiments, I handled 

 more than 25 kg. of the plants, and several hundred persons 

 passed through the laboratory, where these experiments were 

 made, but not one of those who did not come in direct contact 

 with the plants or the free oil was poisoned. 



It seems possible that poisoning might be caused by small 

 particles of the plant, such as pollen and the hairs from the 

 leaves, being carried through space by the wind and thus brought 

 in contact with the skin or clothing, for, as above stated, the 

 oil is contained in all parts of the plant, and even the hairs of the 

 leaves may be seen under the microscope to contain oil. 



Having defined the properties of " Toxicodendrol " we may 

 now outline the rational treatment of ivy poisoning. As we have 

 said, "Toxicodendrol " is not a volatile oil, but, on the contrary, 

 is very stable ; we must endeavour to remove it as quickly as 

 possible and prevent its spreading. 



