CHAPTER VI 



REPRODUCTION AND HEREDITY 



Our discussion on Behaviour in the previous chapter has 

 suggested that many of the actions performed by insects 

 depend upon the constitution which they inherit through 

 their parents and ancestors ; the insect comes into the 

 world with its nervous and other systems " set " in special 

 ways, so that its behaviour is as a rule like that of its parents 

 under similar conditions. It is also obvious and generally 

 recognised that in^sects — like other living creatures — 

 resemble their parents in form and structure even to 

 minute details ; yet beginners in the study of such insects 

 as the moths belonging to certain groups quickly realise 

 that even among a family reared from the same batch of 

 eggs there may be a considerable degree of individual 

 variation. All living creatures arise as the offspring of 

 pre-existing living creatures. It is of interest to recall that 

 less than two centuries ago many learned men beHeved and 

 taught that such insects as maggots might be ** bred " or 

 *' spontaneously generated " by dirt or carrion, although 

 these beliefs had long before been confuted by F. Redi 

 (1671), who showed that the maggots which feed in flesh 

 develop into flies, and that no maggots can appear in flesh 

 which is carefully screened so that flies cannot lay eggs on 

 it. The genetic chains of living creatures around us, and 

 including indeed our own race, are so familiar as part of 

 our accepted world that we readily overlook the problems 

 that present themselves when we consider the means by 

 which inherited characters, whether of form, appearance, or 

 behaviour, are passed on through the successive generations 



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