F 
Cen.) 
is—first the piercing-power, then the splitting-power, and 
lastly the lacerating-power. 
These are combined in an instrument which may in certain 
respects resemble, but cannot be identified with, any tool 
employed by human artificers unless it similarly combines 
them. The usual comparison to a éenon saw is particularly 
unsatisfactory, as suggesting that the “support” takes no 
active share in the process, and also, prima facie at least, 
suggesting that it accompanies the movements of the “ saws.” 
Finally, any notion of the tool is misleading which makes 
us think of it simply as a plate, or pair of plates. It is 
emphatically an object of three dimensions, and all must 
be taken into consideration before we can form opinions as 
to its mechanical potentialities and probable action and their 
consequences. 
On commencing the inquiries of which this Address is the 
outcome I consulted, and often copied out in extenso, a great 
many descriptions of the process contained in the works of 
celebrated scientific authors. Looking now over these extracts 
in the light of my subsequent investigations, truth compels 
me to say that in nearly all of them a few grains of truth are 
combined with an immense amount of misunderstandings and 
misleading suggestions. Several of them make no profession 
to rest on any special investigation of the phenomena by their 
authors, but are frankly simple compilations. These I may 
pass over; but one or two, which have been put forth by 
really outstanding scientific authors as embodying truths 
before unknown which they have discovered in their own 
researches or can vouch for as having been accepted by them 
on sufficient evidence, contain what appear to me such mis- 
leading notions that it would be false modesty to shrink 
from commenting upon them. Thus, I take up two standard 
text-books on Microscopy, each of them the work of a justly 
celebrated author, a pioneer in more branches of science than 
one, and a Fellow of the Royal Society. 
1.—One of these authors describes at great length the 
microscopical characters of ‘The Saw of the Sawfly.” He 
gives figures, in which I believe I can recognise with con- 
fidence two portions of the organ in question as it exists in 
