vii] HEREDITY 93 



stincts in connexion with egg-laying, yet the process 

 may last only a few hours, and the eggs may all be 

 fully formed and ready for laying before the insect 

 hatches. In the worker-bee, too, there are many 

 admirably developed instincts, and also structural 

 features which might be thought to have originated 

 by the transmission of acquired adaptations, and yet 

 the worker-bee, except in rare cases, never repro- 

 duces itself, but is produced by a queen and a drone 

 with structures and instincts different from its own. 

 If in these cases we find perfect instincts which 

 cannot have arisen by the inheritance of acquire- 

 ments, it seems unreasonable to assume that instincts 

 in other species must have arisen in this way. These 

 two cases are given merely as examples of the pre- 

 sumptive evidence that has been brought forward. 

 It is admitted that the process of evolution would 

 be more easily comprehensible if the inheritance 

 of acquired characters were a fact, but it is clear 

 that no absolute proof of its existence can be based 

 on cases of this kind. 



Exact experiments on the possible inherited 

 effects of acquirements are difficult to devise so as 

 to be unequivocal, and most have given negative 

 results. Experiments on butterflies have been men- 

 tioned in Chapter in, so further reference to them is 

 not required. A case which at first sight seems to 



