272 The American Naturalist. [April, 
Among the more important problems of plant biochemistry 
are the chemical nature of chlorophy]l, the nature and manner 
of action of the starch-forming substance, the determination of 
the substances out of which the plant synthesizes its protoplasm, 
and the nature of this synthesis. In bacteriology the biochem- 
ist has a wide field for work. The isolation of the specific im- 
munizing substance in the antitoxins of diphtheria, tetanus 
and other cases of artificial immunity, is a matter of great 
practical importance. There is pressing need of a chemical 
examination of the bacteria and their products, whether poi- 
sonous or not. The determination of the active substance in 
such bodies as the tubercle bacilli, which cause cell prolifera- 
tion, is an interesting matter which might havea considerable 
practical value. 
In physiology, biochemistry has hitherto played its chief 
role in the study of excretion and digestion. The results ob- 
tained have thrown light on the functions of many organs. An 
interesting question of physiology at the present time is that of 
the internal secretions of glands. It is becoming increasingly 
probable that these form an important element in the coördi- 
nation of the organism, one organ or gland forming and throw- 
ing back into the blood substances essential to the life of some 
other organ. The determination of these substances, of such 
preeminent importance to the organism, is a biochemical 
problem. The isolation of the contractile substance in muscle, 
the chemical changes undergone by muscle and nerve during 
activity, the nature of the irritable substance of the nervous 
system, are puzzles which fall to the biochemist. Our knowledge 
of the chemical constitution of the fluids and tissues of the body 
in health and disease is derived from this science. 
In the province of biology the ultimate aim, however distant 
the goal may be, is the analysis and synthesis of living matter 
itself. The explanation of the formation of new protoplasm 
will probably come from the biochemist. He must isolate and 
examine the various substances in the cell. That this field is 
full of promise is evident from the results already obtained. 
Morphology, too, furnishes its quota of problems. The influence 
of certain substances upon embryonic development is in part 
