CABBAGE WHITE BUTTERFLIES 165 



little alteration of form, only increase in size, is to be 

 observed. The last moult, however, appears suddenly 

 to convert the larva into a new being. 



I say " appears," because, as we now know, the pupa 

 is merely the larva in a new form. Pupation is a change 

 of skin, accompanied by an unusual amount of change 

 of form. When the last larval skin is cast, the 

 rudiments of wings and other new parts become 

 visible, though they do not acquire their ultimate 

 structure nor serve any useful purpose until the 

 resting-stage is over, when, after one more moult the 

 winged Insect emerges. 



This seems plain enough to any one who observes 

 for himself. Yet much controversy was needed and 

 much Christian ink had to be shed before men could 

 be persuaded to drop their theories and look the facts 

 in the face. 



When our Royal Society was founded the wildest 

 notions were abroad as to generation, development 

 and transformation. If the reader should chance to 

 come across a curious but rather worthless book 

 published in 1634, Moufet's (or Mouffet's) Theatrum 

 Insectorum, he will find in the dedicatory epistle by 

 Sir Theodore de Mayerne much learned trash about 

 the universal spirit which fills and governs the three 

 kingdoms of Nature. If animals and plants undergo 

 transmutation, Mayerne does not see why it should 

 be impossible for metals to do the same. In 1651 

 Harvey, our great Harvey, published his treatise on 

 Generation, and here, as all the world knows, is solid 

 matter, the fruit of observation and reflection upon 

 the development of chicks and fawns. But 



