42 THE MYSTERY OF LIFE. 



the right of a compound fibre crosses over to 

 the left, and then again traverses the branch to 

 reach the opposite side, and so on through the 

 whole length of the fine nerve fibres. This 

 arrangement is constant in all nerves, and is 

 observed in large trunks as well as in the finest 

 ramifications. Will anyone believe that a fact 

 so constant is meaningless, a result of accident 

 to be explained by subtle influences, or natural 

 selection ? Shall we account for the fact by 

 attributing it to the operation of a physico-spiral 

 tendency, or dismiss it with the announcement 

 that the law of nerve reticulation will be dis- 

 covered ere long ? But it is marvellous how 

 difficult it is even to obtain assent to an impor- 

 tant but simple fact of observation of this 

 kind. Every student who has dissected a 

 nerve knows that the nerve fibrils cross and 

 intertwine in the trunk. A low magnifying 

 power only is required to convince him that the 

 same fact is observed in the smaller trunks. 

 Careful examination of properly prepared speci- 

 mens will prove that the disposition is the same 

 in still more minute ramifications ; and I possess 

 numerous preparations in which the same point 

 may be demonstrated in the most minute nerve 



