8 



order of chemical changes is appreciated with scientific 

 precision, and the phenomena of heat, light, and electricity 

 are gradually being unfolded and revealed. The phenomena 

 of inheritance, however, although recognised to some extent, 

 as I have said, from the earliest ages, have but recently been 

 subjected to such analysis as enables us to refer them to a 

 biological law ; and, notwithstanding that this must be 

 regarded as a later, and less perfect revelation, when com- 

 pared with the other sets of phenomena to which I have 

 alluded, yet the phenomena of inheritance are by degrees 

 finding interpretation, and in all probability the grand law of 

 heredity will ere long be as well recognised, and as firmly 

 established as any of the so-called laws of the universe. 

 " Natural laws," says Dr. Carpenter, " can only be regarded 

 as the general expression of the conditions under which 

 certain assemblages of phenomena occur, so far as those 

 conditions are known to us ;" or in the words of Mr. Lewis, 

 "the paths along which forces travel to their particular 

 results." If phenomena be reducible to a law, their inves- 

 tigation constitutes a science. Science can only deal with 

 phenomena and experience ; and when we come to regard 

 the ultimate causes of any of these groups of natural phe- 

 nomena, and find them not reducible to law, they must be 

 attributed to the supernatural, as science pauses paralysed 

 at the very threshold of such an inquiry. The conditions 

 under which the phenomena of inheritance occur, in so far 

 as they are known, enable us to group these phenomena so 

 that their general expression represents a law ; and in pro- 

 portion as these groups can be accurately defined and in- 

 terpreted, they are the effects of the biological law of here- 

 dity, just as the phenomena of gravity are of the great law 

 of gravitation. 



