THE MORE IMPORTANT PLANT PRODUCTS 71 



to be due to the action of a ferment, to which the name laccase 

 has been appHed, which is only active in a certain humidity of 

 the atmosphere. Quite recently, however, the presence of a 

 special ferment has been questioned, and the absorption of 

 oxygen attributed to an obscure chemical reaction depending on 

 the presence of a compound of manganese with a proteid-like 

 substance. Chinese lacquer, in a raw state, unfortunately 

 possesses properties which are poisonous to many people, pro- 

 ducing swellings and eruptions of the skin in the same way as 

 does its close ally, the "Poison Ivy" {Rhus Toxicodendron). 

 Certain people are immune, but this property will probably 

 always militate against its use in Western lands. Perhaps the 

 chemists wiU one day discover a means whereby this poisonous 

 property can be neutralized or eliminated. 



The fruit of R. verniciflua is shining, greyish-yellow, 

 roundish and flattened on two sides, 6 to 10 mm. long. These 

 when crushed and treated in a wedge-press in the same way 

 as wood oil seeds, yield a fatty oil known as " Che-yu," 

 which is used for making candles. 



Trees belonging to three different families produce fruits 

 rich in saponin which are in common use for laundry-work and 

 other purposes. The most generally distributed of these 

 " Soap trees " is Gleditsia sinensis, a handsome tree known col- 

 loquially as " Tsao-k'o shu," abundant throughout the Yang- 

 tsze Valley up to 3500 feet altitude. It grows 60 to 100 feet 

 tall, and has a thick trunk, smooth grey bark, a spreading head 

 with massive branches, furnished with small, pinnate leaves and 

 inconspicuous greenish flowers, unisexual or hermaphrodite in 

 character. The latter are followed by pods or " beans " which, 

 when ripe, are black, 6 to 14 inches long and f to n^ inch wide. 

 These pods are broken up and are in general use for ordinary 

 laundry-work, producing a good lather in either cold or hot 

 water. They are also used in the process of tanning hides. 

 The saponaceous fat is contained in the pod itself, which is 

 the only part utilized, the hard, flattened, brown seeds being 

 discarded. It is probable that more than one species is included 

 under the above name, for the Gleditsia family is in need of 

 revision. In Yunnan another species which has much larger 

 (20 inches) and wider pods is employed for the same purposes. 



