270 BOTANICAL GAZETTE [MarcH 
noticed and is plainly schizogenous. Some of the secreting cells 
may eventually break down altogether, to leave their secretions in 
the cavity formed by their disintegration and thus be designated 
lysigenous in character. Cavities so appearing in my investigations 
of this plant may have been due to imperfect sections. At any 
rate, lysigenous cavities are apparently in the minority. 
If these observations be compared with previous works on other 
Anacardiaceae, it will be seen that there are no essential differences 
in the arrangement of the intercellular secretory reservoirs. Which 
genera should be poisonous, or why their poisons should vary, either 
in physiological action or in chemical composition, cannot be 
deduced from this part of their anatomies. 
Plants other than the Anacardiaceae that secrete resin, emul- 
sions of gum-resin, etc., in passages are as follows: Coniferae, 
Alismaceae, Aroideae, the tubifloral Compositae, Umbelliferae, 
Araliaceae, Pittosporeae, many species of Mamillaria, Clusiaceae, 
and Ailantus and Bruceae of the Simarubeae. 
The abundance and comparatively large size of the resin ducts, 
together with their fusing, make an intercommunicating system. 
When a wound is made, the sap and its poison are quickly pressed 
out, either by the tension of the elastic walls of its own cells or by 
a combination of both. In the spring the sap is very watery, 
while the autumn product is much thicker, granulous, and slower 
in exudation. The sap, which is properly an emulsion, is, when 
first expressed, white or light gray in color, and as it quickly 
coagulates and browns in the air, it forms an efficient covering for 
the wound. The sap is darkened in the air mainly by oxidation, 
as has been shown in a former paper (3): first, when deprived of 
oxygen the sap darkens but very slowly; secondly, when in the 
presence of oxygen the sap darkens rapidly; and finally, ultimate 
chemical analyses of the sap before and after darkening show an 
appreciable difference only in the oxygen content. 
Under the microscope the freshly exuded sap is in part a colorless 
liquid and in part made up of minute globules. Very soon some 0 
these globules become dark brown, while the fewer remaining 
globules continue to be colorless. While this change has been 
taking place, oblong rectangular colorless crystals separate out. 
The first crystals to separate are larger than those which form 
