FATS FROM RHUS LAURINA AND RHUS DIVERSILOBA! 
JAMES B. McNAIR 
(WITH ONE FIGURE) 
STEVENS (12) has noticed that the green fruit of Rhus radicans 
is very poisonous. STEVENS and WARREN (13), when investigating 
the fruit of R. vernix, found the green fruit highly toxic, while the 
ripe fruit is harmless. WARREN (15) attributes this interesting 
change in toxicity to an apparent replacement of acrid resins by 
wholesome and palatable fats. Besides these species of Rhus, a 
fat (Japan wax) has been found in 4 species of Rhus: R. succedanea 
.. R. acuminata DC., R. vernicifera DC., and R. sylvestris Sieb. and 
Zucc. (6). All 6 of these species are poisonous, and it is interesting 
to note that the discovery of fat in the fully matured fruit of Rhus 
laurina Nutt. may add a non-poisonous species to the list. 
Investigations were begun by me on the fats from Rhus laurina 
Nutt. and R. diversiloba T. and G. with two objects in view: (1) to 
discover whether or not these fats are identical with Japan wax, 
and (2) to determine, if possible, the connection between this fat 
and the poisonous property of R. diversiloba. This latter problem 
appeared all the more interesting when the fact became apparent 
that during the ripening of the drupes their poisonous properties 
simultaneously decreased with their increase in fat. When the 
fruits have reached full maturity (when the semi-transparent 
epidermis loosens and easily falls off from the waxy mesocarp) 
they are non-toxic. The toxicity was tested by thoroughly rubbing 
the pulverized fruits, as well as an alcoholic solution from them 
(concentrated to one-third of the original volume of the fruits), on 
the skin of a sensitive person. 
The fats experimented with were obtained by boiling the ripe 
fruits in 95 per cent alcohol under a reflux condenser. The fat 
samples were purified by repeated solution, evaporation of the 
«Contribution from the Rudolph Spreckel’s Physiological Laboratory of the 
University of California. 
Botanical Gazette, vol. 64] [33° 
