480 FRAGMENTS OF SCIENCE. 
of psychology; and two years ago a second and greatly 
amplified edition of his work appeared. Those who have 
occupied themselves with the beautiful experiments of 
Plateau will remember that when two spherules of olive-oil 
suspended in a mixture of alcohol and water of the same 
density as the oil, are brought together, they do not 
immediately unite. Something like a pellicle appears to 
be formed around the drops, the rupture of which is 
immediately followed by the coalescence of the globules 
into one. There are organisms whose vital actions are 
almost as purely physical as the coalescence of such drops 
of oil. They come into contact and fuse themselves thus 
together. From such organisms to others a shade higher, 
from these to others a shade higher still, and on through 
an ever-ascending series, Mr. Spencer conducts his argu- 
ment. There are two obvious factors to be here taken into 
account the creature and the medium in which it lives, 
or, as it is often expressed, the organism and its environ- 
ment. Mr. Spencer's fundamental principle is, that be- 
tween these two factors there is incessant interaction. The 
organism is played upon by the environment, and is 
modified to meet the requirements of the environment. 
Life he defines to be "a continuous adjustment of internal 
relations to external relations." 
In the lowest organisms we have a kind of tactual sense 
diffused over the entire body; then, through "impressions 
from without and their corresponding adjustments, special 
portions of the surface become more responsive to stimuli 
than others. The senses are nascent, the basis of all of 
them being that simple tactual sense which the sage Demo- 
critus recognized 2,300 years ago as their common progen- 
itor. The action of light, in the first instance, appears 
to be a mere disturbance of the chemical processes in the 
animal organism, similar to that which occurs in the leaves 
of plants. By degrees the action becomes localized in a 
few pigment-cells, more sensitive to light than the sur- 
rounding tissue. The eye is incipient. At first it is merely 
capable of revealing differences of light and shade produced 
by bodies close at hand. Followed, as the interception of 
the light commonly is, by the contact of the closely ad- 
jacent opaque body, sight in this condition becomes a 
kind of " anticipatory touch." The adjustment con- 
tinues; a slight bulging out of the epidermis over the 
