86 
INTRODUCTION. 
transmutation, or change from one being to another 
Such an opinion presented no difficulties to those 
who, like Virgil, imagined that a swarm 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. 
