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ception of an insect which saws wood as we do, but with an 
implement which is not only adapted but “ideal” for that 
purpose, and which, but for its perfections and minuteness, 
would be identical with the saws of human carpenters— 
surely this is the ne plus ultra of Teleology and Anthropo- 
morphism combined. 
So much for the causes of its popularity, but how have thay 
affected its truth? Mainly, it seems to me, as follows. 
To all intents and purposes the whole of the literature from 
which English readers, except a few specialists, derive their 
ideas upon the subject has arisen out of a single set of observa- 
tions—those of Réaumur on a species previously undescribed, 
but identical, in my opinion, beyond a doubt with what is 
now known all over Europe as Arge (or Hylotoma) rosae of 
De Geer. 
These observations were made with extreme care and com- 
pleteness in every respect, and reported in the minutest detail. 
Réaumur watched repeatedly the living insect in the act of 
excavating fresh shoots of the rose, and subsequently laying 
an egg in the excavation. He tells us exactly what he saw 
from first to last, how much with the naked eye, and how 
much with lenses, how the insect stood and generally com- 
ported itself, how and when precisely the “saw” became 
visible, how it entered the stem, and how much he could see, 
or was at times unable to see, of the movements made by it. 
Besides this, he gives a number of figures (which I reproduce 
in the plates appended to this Address) showing both sexes of 
the insect, the excavations, the eggs, and the instrument used 
in the operation—this instrument as a whole, and also its 
separate component parts and attachments to the body, being 
shown in several different aspects, and at various magnifica- 
tions. In every single positive statement made by him as to 
the facts which he observed he is, I feel certain, absolutely to 
be trusted. Only it must not be forgotten that he only pro- 
fesses to record the operations of a single species, and that he 
distinctly affirms his belief that not all Sawflies work in exactly 
the same manner. 
It is only when Réaumur sums up the general impressions 
made upon him by his observations, that an unprejudiced 
