igS PRESENT-DAY RATIONALISM 



being suited for a submerged life. Other plants, as the water 

 milfoil, do the same thing. 



On the other hand, some species have degenerated to a 

 greater degree so that they have lost this power of adaptation. 

 Such I found to be the case with 7?. circinatus (?) and Elodea 

 canade7isis, both of which sent up several shoots into the 

 air when grown in a bowl of water ; but in no case were aerial 

 leaves produced, as they shrivelled up at once and perished 

 just as sea-weeds do. 



I think the reader will now see that coincidences between 

 the divided modification of the leaf-blade with normal sub- 

 mergence are as numerous as the agreements between the 

 absorption bands in the solar spectrum and the coloured bands 

 of vapourised elements. 



If the induction is perfectly legitimate in the latter it must 

 be equally so in the former, which has the additional aid of 

 experimental corroboration. The inevitable conclusion is that 

 the dissected type of foliage seen in these submerged leaves is 

 the " actual modification " produced by the watery medium in 

 which the plants live. That is to say, the latter is the stimulus 

 to which the living protoplasm responds and has brought about 

 the structure in question. 



Mr. Herbert Spencer expressed this in his generalisation : 

 " Under new conditions the organism immediately begins to 

 undergo certain changes in structure fitting it for its new con- 

 ditions ". 



The next point to notice is that the dissected leaf is 

 hereditary. When I brought this case of the dissected foliage 

 of submerged plants before my Darwinian friend he observed : 

 " Experimental evidence of the truth of your view as to the 

 submerged leaves of dicotyledons is still lacking". He is not 

 alone in not realising the fact that the above inductive evidence 

 was amply sufficient to establish a natural law, and really needs 

 no experimental evidence ; still, as such has now been obtained, 

 it is satisfactory to find that the inductive evidence was correct 

 and conclusive without any experiment at all. 



