120 TIIE DATA OF BIOLOGY. 



agency of a nervous system, many cooperations of parts are 

 achieved in ways that are superficially comprehensible, we 

 still meet with various actions of which the causation cannot 

 be represented in thought. Lacking other calcareous matter, 

 a hen picks up and swallows bits of broken egg-shells; and, 

 occasionally, a cow in calf may be seen mumbling a bone she 

 has found evidently scraping off with her teeth some of its 

 mass. These proceedings have reference to constitutional 

 needs; but how are they prompted? What generates in the 

 cow a desire to bite a substance so unlike in character to her 

 ordinary food? If it be replied that the blood has become 

 poor in certain calcareous salts and that hence arises the 

 appetite for things containing them, there remains the ques 

 tion How does this deficiency so act on the nervous system 

 as to generate this vague desire and cause the movements 

 which satisfy it ? By no effort can we figure to ourselves the 

 implied causal processes. 



In brief, then, we are obliged to confess that Life in its 

 essence cannot be conceived in physico-chemical terms. The 

 required principle of activity, which we found cannot be 

 represented as an independent vital principle, we now find 

 cannot be represented as a principle inherent in living 

 matter. If, by assuming its inherence, we think the facts 

 are accounted for, we do but cheat ourselves with pseud- 

 ideas. 



3Ge. What then are we to say what are we to think? 

 Simply that in this direction, as in all other directions, our 

 explanations finally bring us face to face with the inex 

 plicable. The Ultimate Eeality behind this manifestation, as 

 behind all other manifestations, transcends conception. It 

 needs but to observe how even simple forms of existence are 

 in their ultimate natures incomprehensible, to see that this 

 most complex form of existence is in a sense doubly incom 

 prehensible. 



For the actions of that which the ignorant contemptuously 



