86 INTRODUCTION. 



transmutation, or change from one being to another. 

 Such an opinion presented no difficulties to those 

 who, like Virgil, imagined that a swai-m of honey- 

 bees might be generated from a piece of putrid flesh ; 

 or, like Kircher, that a crop of serpents might be 

 reared from cut pieces of snakes, roasted, and sown 

 in an " oleaginous soil ;" and may even now seem 

 not untenable by such as believe that a horse-hair 

 placed in the water of a spring will, in process of 

 time, be transformed into a hair-worm, or young 

 eel ! The accurate investigations of Malpighi and 

 Swammerdam were the first to show this subject in 

 its true light, by demonstrating in what the trans- 

 formations of butterflies essentially consist. By the 

 dissection of caterpillars — an operation which they 

 performed with astonishing skill and delicacy — they 

 were able to discover the parts of the future butter- 

 fly folded up within the body, in the same manner 

 as an embryo flower may be detected in the interior 

 of an unexpanded bud. " It is clearly and distinct- 

 ly seen," says Swammerdam, " that within the skin 

 of the caterpillar a perfect and real butterfly is hid- 

 den, and therefore the skin of the caterpillar must 

 be considered only as an outer garment, containing 

 in it parts belonging to the nature of a butterfly, 

 which have grown under its defence by slow degrees, 

 in like manner as other sensitive bodies increase by 

 accretion." * In every caterpillar, therefore, there 

 exists, from the earliest period of its life, the germ 

 ■ Book of Nature, ii. 26 



