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 s^ojierules 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 j^ellicle 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 sageDemo- 

 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 



