252 PLANT AND ORGANIC CHEMISTRY 
Comparing the Cycadese and Palmae, the former are differ¬ 
ently placed by different botanists, but the general resemblance 
is remarkable, and they both yield sago. 
Chemical constituents of plants are found in varying quan¬ 
tities during stated periods of the year. Certain compounds 
present at one stage of growth are absent at another. Many 
facts could be brought forward to show the different chemical 
composition of plants in different stages of growth. The Thuja 
occidentalism in the juvenescent and adult form, offers an ex¬ 
ample where morphological and chemical differences go hand 
in hand. Analyses of this plant under both conditions show 
a striking difference. 
Different parts of plants may contain distinct chemical com¬ 
pounds, and the comparative chemical study of plant orders 
comprises the analysis of all parts of plants of different species. 
For example: four portions of the Yucca angustijolia 1 2 were 
examined chemically—the bark and wood of the root and the 
base and blades of the leaves. Fixed oils were separated from 
each part. These were not identical, — two were fluid at or¬ 
dinary temperature, and two were solid. Their melting and 
solidifying points were not the same. 
This difference in the physical character and chemical re¬ 
action of these fixed oils may be due to the presence of free 
fatty acid and glycerides in varying proportions in the four 
parts of the plants. It is of interest to note that, in the subter¬ 
ranean part of the Yucca , the oil extracted from the bark is 
solid at the ordinary temperature; from the wood it was of a 
less solid consistency; while the yellow base of the leaf con¬ 
tained an oil quite soft, and in the green leaf the oil is almost 
fluid. 
Two new resins were extracted from the yellow and green 
parts of the leaf. It was proposed to name them yuccal and 
pyrophceal. An examination of the contents of each extract 
showed a different quantitative and qualitative result. 
Saponin was found in all parts of the plant. 
Many of the above facts have been collected from the in- 
1 Meehan, Proc. Acad. Nat. Sciences. 
2 H. C. De S. Abbott, Trans. Amer. Philos. Soc., 1886. See p. 126. 
