156 CLUES AND SUGGESTIONS CHAP. 



in strength when the set time had come, 

 and very probably to appear in embryo 

 even sooner. 



It has always appeared to me that 

 this is a conception of such strength, and 

 even of such certainty, that it casts a 

 new and a very clear light on one of the 

 most curious and puzzling groups of fact 

 which the science of Biology reveals 

 I allude to the frequent occurrence in 

 animal structures of what are called 

 rudimentary organs that is to say, the 

 occurrence of bits of organic mechanism 

 which are never to be used in that 

 particular creature, but which, in other 

 creatures widely different, grow up into 

 functional activity, and may even be the 

 most essential organs of its life. A great 

 number of instances have been cited by 

 comparative anatomists some of them, 

 perhaps, more fanciful than real as, for 

 example, when the five or six vertebrae 



