474 . The American Naturalist. [June, 
ago, the well-known Oxford physiologist, Burdon Sanderson, 
wrote concerning the nature of the physiological inquiry, 
“The work of investigating the special functions, which, dur- 
ing the last two decades, has yielded such splendid results, is 
still proceeding, and every year new ground is being broken 
and new and fruitful lines of experimental inquiry are being 
opened up; but the further the physiologist advances in this 
work of analysis and differentiation, the more frequently does 
he find his attention arrested by deeper questions relating to 
the essential endowments of living matter, of which even the 
most highly differentiated functions of the animal or the plant 
organism are the outcome.” Again, “ No one who is awake to 
tendencies of thought and work in physiology, can fail to have 
observed that the best minds are directed with more concen- 
tration than ever before to those questions which relate to the 
elementary endowments of living matter, and that if they are 
still held in the background, it is rather because of the ex- 
treme difficulty of approaching them than from any want of 
appreciation of their importance. * * * * If we really 
understood them, they would furnish a key, not only to the 
phenomena of nutrition and growth, but even to those of re- 
production and development. * * * * It is in the direc- 
tion of elementary physiology, which means nothing more 
than the study of the endowments of living material, that the 
advance of the next twenty years will be made.” 
Regarding the need of a cellular physiology, it is only nec- 
cessary to review our knowledge of any one of the complicated 
organs to perceive that aside from the principles, often chiefly 
mechanical, involved in the work of the organ as 4 whole, the 
essence of its activity lies in the activity of its component cells. 
The work of the muscle, e. g., is the sum of the activities of its 
constituent physiologically similar fibres. A single gland ce 
illustrates the principles of secretion as well as, or eve? better 
than, a thousand grouped together into a compact gland. The 
complexity of brain operations is due to the complexity i 
brain strueture, but the active agents are the comparat ti 
simple nerve-cells. Huxley sets forth as the first three of t ° 
five chief ends of modern physiology: “ Firstly, the ascertain 
