ADDRESS. Ixxxix 
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 en- 
vironment. Mr. Spencer’s fundamental principle is, that between 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 ex- 
ternal relations.” 
In the lowest organisms we have a kind of tactual sense diffused over the 
entire body ; then, through impressions from without and their correspond- 
ing 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 Democritus recognized 2300 years 
ago as their common progenitor. 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 surrounding tissue. The eyeis here 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 is in almost all cases by 
the contact of the closely adjacent opaque body, sight in this condition 
becomes a kind of ‘anticipatory touch.” ‘The adjustment continues ; a slight 
bulging out of the epidermis over the pigment-granules supervenes. A lens 
is incipient, and, through the operation of infinite adjustments, at length 
reaches the perfection that it displays in the hawk and eagle. So of the 
other senses ; they are special differentiations of a tissue which was originally 
vaguely sensitive all over. 
With the development of the senses the adjustments between the organism 
and its environment gradually extend in space, a multiplication of expe- 
riences and a corresponding modification of conduct being the result. The 
adjustments also extend in time, covering continually greater intervals. 
Along with this extension in space and time the adjustments also increase 
in speciality and complexity, passing through the various grades of brute 
life, and prolonging themselves into the domain of reason. Very striking 
are Mr. Spencer’s remarks regarding the influence of the sense of touch 
upon the development of intelligence. ‘This is, so to say, the mother-tongue 
of all the senses, into which they must be translated to be of service to 
the organism. Hence its importance. The parrot is the most intelligent of 
birds, and its tactual power is also greatest. From this sense it gets know- 
* ledge unattainable by birds which cannot employ their feet as hands. The 
elephant is the most sagacious of quadrupeds—its tactual range and skill, and 
the consequent multiplication of expericnces, which it owes to its wonderfully 
adaptable trunk, being the basis of its sagacity. Feline animals, for a similar 
cause, are more sagacious than hoofed animals,—atonement being to some 
extent made, in the case of the horse, by the possession of sensitive prehensile 
lips. In the Primates the evolution of intellect and the evolution of tactual 
appendages go hand in hand. In the most intelligent anthropoid apes we 
find the tactual range and delicacy greatly augmented, new avenues of know- 
ledge being thus opened to the animal. Man crowns the edifice here, not only 
in virtue of his own manipulatory power, but through the enormous extension 
of his range of experience, by the invention of instruments of precision, which 
serve as supplemental senses and supplemental limbs. The reciprocal action of 
these is finely described and illustrated. That chastened intellectual emotion 
to which I have referred in connexion with Mr. Darwin is not absent in Mr, 
