THE BELFAST ADDRESS 



35 



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 argument. 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 

 environment. Mr. Spencer's funda- 

 mental 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 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 sur- 

 face 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 

 recognised 2,300 years ago as their 

 common progenitor. The action of light, 

 in the first instance, appears to be a 

 mere disturbance of the chemical pro- 

 cesses in the animal organism, similar to 

 that which occurs in the leaves of plants. 

 By degrees the action becomes localised 

 in a few pigment-cells, more sensitive to 

 light than the surrounding 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 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 adjust- 

 ments, at length reaches the perfection 

 that it displays in the hawk and eagle. 

 So of the other senses ; they are special 



1 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 experiences and 

 a corresponding modification of conduct 

 being the result. The adjustments also' 

 extend in time, covering continually 

 greater intervals. Along with this exten- 

 sion 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 trans- 

 lated 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 saga- 

 cious of quadrupeds its tactual range : 

 and skill, and the consequent multiplica- 

 tion 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 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 



