274 LEISURE-TIME STUDIES. 



the origin of nerves, and to set before us some reasonable 

 ideas concerning the conditions in living beings which have 

 favoured, inaugurated, and perfected the most complex part 

 of our physical belongings. In such a study we may per- 

 chance touch upon several issues which lie very near to 

 some weighty matters connected with mind and brain ; 

 whilst in any case the subject itself is one of the most 

 attractive which can be presented to the thinking mind. 



A few words concerning the functions of a nervous sys- 

 tem, wherever found, and in whatever degree of perfection 

 it may exist, may form a suitable introduction to the topic 

 which awaits our study. Shortly expressed, the function of 

 nerves is that of bringing their possessor into relationship with 

 the outer world. This result is attained through the especial 

 property of nerves, termed " irritability " by the physiologist, 

 a term which, in unconscious sarcasm, might be, and is, 

 applied to indicate an excess of nerve-action in humanity 

 itself. Through the property of irritability, and of respond- 

 ing to impressions made upon them by the outer world, 

 nerves affect the parts in which they are distributed ; whilst 

 through their action on these parts, they may in turn affect 

 the entire body of their possessor. But the simple observa- 

 tion of any common action in man and lower animals will 

 serve to show that there exists a wonderful sameness of 

 working, so to speak, in the nervous acts of high and low 

 forms of animal life. When a blow is aimed at the face, or 

 when the hand of a bystander is passed rapidly before our 

 eyes, the result of these actions in ourselves respectively 

 consists in the withdrawal of the head and in the closure of 

 the eyes. If we endeavour to rightly comprehend what is 

 implied in these actions, we shall have laid a sure basis for 

 the further understanding of how nerves act in well-nigh 

 every detail of life. 



The blow or threat which comes from the bystander, 

 represents an " impression " of the outer world made upon 

 a special portion of our nervous system, the sense and 

 organ of sight. It is the function of these organs to receive 



