800 Comparative Chemistry of Higher and Lower Plants. 
COMPARATIVE CHEMISTRY OF HIGHER AND | 
| LOWER PLANTS.. ae 
BY HELEN C, DE S ABBOTT. 
(Concluded from page 730.) 
jee laws controlling the chemical evolution of plant-consii 
uents are too little comprehended to formulate, but befor 
reaching a position ever to do this, it will be necessary to study 
carefully the facts from extended researches, to ascertain how 
these chemical constituents occur, under what conditions, and if 
these conditions are constant or variable, and to what may% 
3 
e hypothesis of evolution, is still too new to possess a litera 
of its own. 
I have already referred to the protoplasm and starch, als? 
the large ash-percentages of some of the lower groups, 
among the compounds commonly found in many plants 
thi 
and correlated with special physiological functions: 
: The general distribution of chlorophyll, with few € a 
in all plant groups is only second to the proteid comp? 
however, the color of this compound is not the same 
plants, and the evergreens and many other plants when co", 
will be found in this respect distinct. The gradual chang? 
the bright greens of the early spring foliage to the duller | 
