THE BEL FAST ADDR ESS. 481 
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 differen- 
tiations 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 experiences and a correspond- 
ing modification of conduct being the result. The adjust- 
ments 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 pro- 
longing 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 knowledge, unattainable by birds 
which cannot employ their feet as hands. The elephant 
is the most sagacious of quadrupeds its tactual range and 
slcill, and the consequent multiplication of experiences, 
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 ap^~ 
pendages go hand in hand. In the most intelligent an- 
thropoid apes we find the tactual range and delicacy greatly 
augmented, new avenues of knowledge 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 sup- 
plemental senses and supplemental limbs. The reciprocal 
action of these is finely described and illustrated. That 
chastened intellectual emotion to which I have referred in 
connection with Mr. Darwin, is not absent in Mr. Spencer. 
His illustrations possess at times exceeding vividness and 
