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NOTES AND MEMOEANDA. 
Insect Digestion and Development . — The Commission of the French 
Academy, reporting upon the researches of M. Jousset de Bellesme, 
to whom the There Prize was assigned, make the following remarks : 
Until lately the plienomena of digestion in insects were but slightly 
illustrated by experience, although some observations inclined to the 
belief that the stomach fluid of insects had the same properties as 
that of vertebrates. Eesearches on the Arachnids, animals closely 
allied to insects, seemed to confirm this opinion. A foreign savant, 
known for some good work, was however led to affirm that the diges- 
tion of insects, whether carnivorous or phytophagous, was effectuated 
under conditions different from those of vertebrates, and he regarded 
the secretions of their digestive tubes as neutral or alkaline. M. de 
Bellesme has made fresh observations, which appear quite decisive. 
Seeing that serious errors are easily made in endeavours to collect the 
fluid secreted by the stomach, he selected insects, such as Blattidae, 
which have stomachs with sufficiently large caecal prolongations to 
allow of the gastric juice being extracted without admixture of other 
matters, and by these means he has shown that the digestion of 
albuminoid substances takes place solely in the stomach, as in the 
case of higher animals. He has produced artificial digestions with 
the acid fluid taken from the caBcal tubes of the stomach. 
By experiments of a similar kind he has demonstrated, as most 
naturalists supposed, that the sole agent for the digestion of amylaceous 
substances is supplied by the salivary glands. 
Another question in insect life has also received from him a final 
solution. Observers have often been astonished to see a winged 
insect of considerable dimensions emerge from a comparatively small 
pupal envelope. The ant lion affords a striking example, and still more 
so the dragonflies and butterflies. At this moment the air filling the 
tracheal tubes, and a sudden activity of the circulation giving rise to 
pressure upon the still soft tegumentary parts, seemed to explain the 
increase of volume, but there was still a difficulty in understanding 
how the wings were unfolded, and on this point the observations of 
M. de Bellesme on dragonflies are conclusive. 
When witnessing the development of flies, Reaumur admitted 
that air was introduced to expand the wings. He said, “ the insect 
drinks in air to fill his body.” Evidently he took no account of the 
way in which the air made its entrance into the insect’s organism, and 
for this reason many authors imagined the remark of the great natu- 
ralist to be without scientific value. Some observers considered the 
expansion of the body and the unfolding of the wings to be caused 
by pressure of the blood, and the fine researches of Mr. J. Kiinckel on 
Volucella demonstrated that an afflux of blood had the result of 
enlarging the head and producing an extension of the wings. He attri- 
buted the movement of the blood to the contractions of the thoracic 
muscles. No doubt, when a fresh activity affects the whole organiza- 
tion, the muscles enter into play ; but the animal is in repose — it has 
not yet taken flight — the muscular action seems too feeble to account 
for the powerful results that are seen. 
