THE BOT OF THE HORSE. 
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the very slight differences which exist, that would incline us to 
consider them as simple varieties rather than as constituting so 
many different species. From what we shall say further on, 
it will in truth appear that there is but a single species, as I 
admit; and that is the one whose larva is found in the 
stomach of the horse, in the duodenum, in the rectum, &c. 
Habits. — Among the immense family of dipteras, the tribe 
of bots is one of the most singular, as well on account of its ap- 
propriate organisation as for its habits, and it is through the 
exterior differences of organs, which serve as the basis to the cha- 
racterisation of these beings, that we find so much divergence 
of description among those who cultivate the natural sciences, 
relatively to the place assigned them in the classification of 
this order of insects ; for if, in some respects, they approach 
the nature of syrpliides , the absence of the horn in some 
species, and the shortness of the antennae, throw them out of 
this division ; if the character of their wings and the ap- 
pendages of their locomotive organs are indications of power 
of flight in certain species ; in others they are found less, and 
cannot on that account be placed together with the antlira , 
from which, again, they differ through modifications in the 
oviduct, simple in some, bifid and complex in others ; often 
very strong, and destined to perforate the skin of the larger 
herbivorous quadrupeds. But my object not being to break 
up dispute on this scientific point, I shall leave it in the 
hands of naturalists. As to the consideration of the pre- 
sence or absence of organs of mastication, a frequent anomaly 
in the order lepidopteric, I shall make no opposition to their 
classification. From recent researches, M. Boisduval, taking 
no longer any account of the buccal organs in this order of 
articulata , observes, in particular, the form of the antennae, in 
order to settle the principal divisions of butterflies. 
In general, all the oestrides live but a short time after they 
come to perfection. After longer or shorter remaining in the 
grub form, transformation takes place into the winged insect ; 
the sexes approach each other, copulate, and, shortly after, the 
male dies. The female becomes engaged in carefully laying 
her eggs ; then she likewise dies. Each species chooses a fit 
place for the future larvae ; but what astonishes most the ob- 
servant naturalist, is to behold the same species changing its 
instinct according to circumstances, while it evinces a know- 
ingness quite extraordinary for the preservation of its progeny. 
The earliest female flies, for example, which appear in the 
autumn (instead of depositing their ova upon the longest 
hairs) if it be wet weather, or if they have not been able to lay 
their eggs as ordinary, or should they be late in their exit, 
