ON HEBEDITY. 93 



certain association of ideas, shot and game, but because he has 

 inherited a reflex mechanism, which impels him to start forward 

 on hearing- a report. We cannot yet determine without more ex- 

 periments how such an impulse due to perception (' Wahrnehmung- 

 strieb,' Schneider) has arisen ; but, in my opinion, it is almost in- 

 conceivable that artificial breeding- has had nothing- to do with it ; 

 and that we are here concerned not with the inheritance of the 

 effects of training- but with some pre-disposition on the part of the 

 germ, which has been increased by artificial selection. 



The necessity for extreme caution in appealing to the supposed 

 hereditary effects of use, is well shown in the case of those 

 numerous instincts, which only come into play once in a life- 

 time, and which do not therefore admit of improvement by practice. 

 The queen-bee takes her nuptial flight only once, and yet how 

 many and complex are the instincts and the reflex mechanisms 

 which come into play on that occasion. Again, in many insects 

 the deposition of eggs occurs but once in a life-time, and yet 

 such insects always fulfil the necessary conditions with unfailing 

 accuracy, either simply dropping the eggs into water, or carefully 

 fixing them on the surface of the earth beneath some stone, or 

 laying them on a particular part of a certain species of plant ; and 

 in all these cases the most complicated actions are performed. It 

 is indeed astonishing to watch one of the Oympidae (Rhodites 

 rosae) depositing her eggs in the tissue of a young bud. She first 

 carefully examines the bud on all sides, and feels it with her legs 

 and antennae. Then she slowly inserts her long ovipositor between 

 the closely-rolled leaves of the bud, but if it does not reach exactly 

 the right spot, she will withdraw and re-insert it many times, until 

 at length, when the proper place has been found, she will slowly 

 bore deep into the very centre of the bud, so that the egg will 

 reach the exact spot, where the necessary conditions for its develop- 

 ment alone exist. 



But each Cynips lays eggs many times, and it may be argued that 

 practice may have led to improvement in this case ; we cannot 

 however, as a matter of fact, expect much improvement in a process 

 which is repeated, perhaps a dozen times, at short intervals of 

 time, and which is of such an excessively complex nature. 



It is the same with the deposition of eggs in most insects. How 

 can practice have had any influence upon the origin of the instinct 



