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XXV. The Foot of the Fly ; its Structure and Action : elucidated by comparison with 
the feet of other Insects, 8fc— Part I. By Tufeen West, Esq., F.L.S. 
March 
1 HE structure and action of the Ply's foot have been so frequently treated of, and are 
so generally considered to be fully understood, that it may appear, at the first glance, as 
if nothing further could be done with so hackneyed a subject. Whilst, however, in con- 
sequence of some investigations which have been recently made to determine its structure, 
opinions may now be considered as pretty well fixed with regard to this portion of our 
subject, authorities still differ widely respecting the action of the parts of which the foot 
is composed. Nor has it appeared that any satisfactory progress was making towards a 
reconcilement of the differences of opinion on the subject, — each succeeding author setting 
aside, more or less, the opinions of his predecessor in point of time, only to be himself 
again contradicted by his successor. On reflection, it occurred to me that this probably 
arose in great measure from the attention of observers having been confined too exclu- 
sively to the Fly's foot, and that perhaps, amongst the teeming myriads of insect-life, 
structures might, on careful search, be met with resembling those under consideration in 
every respect but that of their being on a larger scale. Supposing this to be the case, 
the advantages gained, both for purposes of observation and of reasoning, will be very 
great, as will be best appreciated by those who have had large experience in micro- 
scopic researches on very minute parts. The high powers necessary for investigations 
under such circumstances demand so many appliances in the instrument of research, with 
such great skill in the use of them — all these tending to introduce new sources of error 
that the student feels it a relief indeed when he can assist his mind towards forming con- 
elusive opinions by availing himself of larger examples of similar structures. That this 
advantage may be gained in the present instance will appear to some extent during the 
course of the following remarks, and still more strongly when I come to speak, on a 
subsequent occasion, of other modifications of the parts now to be noticed, of the types 
of feet in Insects which characterize, with few exceptions, the grand divisions in a syste- 
matic classification, and of the analogies and homologies respectively of the parts. It 
is intended now simply to indicate the leading divisions of the subject, and to show that 
parts similar to those on the Ely's foot, but on a larger scale, are to be met with abun- 
dantly in other insects. And, this advantage being gained, it is hoped that a fuller un-^ 
derstanding of the nature and purposes of these structures in the insect economy will also 
be reached, and that the conclusions to be drawn will, from the wider basis^ on which 
they rest, satisfy more completely than hitherto all the conditions of the question. 
It will be necessary to give a brief sketch of the, labours of previous observers on this 
subject, before stating the results of my own investigations. 
The earliest mention which I find of any minute examination of the feet of the Ply is 
