ARTICULATED ANIMALS. 
I 478 
the thorax in the Myriapoda ; but it is distinct in all the other insects which are fur- 
nished with six legs. It incloses the viscera, the sexual organs, and exhibits nine or 
ten segments, but of which some are often concealed, or very considerably reduced in 
size. The organs of generation are situated at its posterior extremity, except in the 
Dragon-flies and luli. The terminal segments of the abdomen compose, in many 
females, an oviduct (oviscapt, Marcel de Serres), which is either retractile or always 
exserted, and more or less complicated, and which is employed as a borer or augur. 
It is replaced by a sting in the females [and neuters] of many Hymenoptera. 
After coupling, which ordinarily takes place but once, the female deposits her eggs 
in the places best suited for their preservation, so that when the young are hatched they 
find themselves in the midst of suitable food. The female also frequently collects pro- 
visions for them. These maternal cares often excite our surprise, and most clearly 
exhibit to us the instinct of insects. In the very numerous societies of many of these 
creatures — such as the Ants, White Ants, Wasps, Bees, &c. — the individuals com- 
posing the majority of the assembly, and which, by their labours and vigilance, support 
these societies, have been considered as neuter individuals, or without sex : they have 
been consequently named workers, or mules. It is, however, now ascertained that 
they are females, of which the sexual organs, or ovaries, are not fully developed, but 
which may become fruitful if a modification of their food, at a certain period of their 
early existence, takes place, whereby these organs are developed. 
The eggs are sometimes hatched in the abdomen of the mother, which is then termed 
viviparous. The number of generations in a year, of a species, depends on the dura- 
tion of each : more commonly, there is but one or two in the year. A species, under 
similar circumstances, is the more common in proportion as its generations succeed 
each other in rapidity, and the female is more fruitful. 
A female Butterfly, after coupling, deposits her eggs, from which are hatched, not 
Butterflies, but animals with a very long body, divided into rings, a head provided with 
jaws, and several little eyes, having very short legs, of which six are scaly and pointed, 
placed in the front of the body, and the others, variable in number, membranous, and 
attached to the hind rings. These animals, called Caterpillars, live a certain time in 
this state, and change the skin several times. At length, however, a period arrives, 
when, from this skin of the Caterpillar, issues a very different being, of an oblong form, 
without distinct limbs, and which soon ceases to move, and remains a long time appa- 
rently dead, and dried up, under the name of a Chrysalis. On regarding it, however, 
mere closely, we perceive, in relief, upon the outer surface of this Chrysalis, the lines 
which represent all the parts of the Butterfly, but in proportions different from those 
which these parts will, at a future day, acquire. After a longer or shorter period, the 
skin of the Chrysalis bursts ; the Butterfly comes forth, moist, soft, with flaccid and 
short wings, but in a few instants it dries, its wings grow, become stronger, and it 
becomes fitted for flight. It has six long legs, antennse, a spiral proboscis, composite 
eyes : in a word, it does not in the least resemble the Caterpillar from which it had 
sprung, for it is ascertained that the changes in its state are nothing else than succes- 
sive developements of the parts contained within each other. Such are the metamor- 
phoses of insects. The first state is named the larva, the second the nymph \jpupa'], 
and the third the perfect state [imago]. It is only in the last- mentioned state that the 
insect is fitted for propagation. 
