ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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concentrated or liquid food they vary greatly, and may even be wanting. 
(2) The valvular function would best explain the thick spiny chitinous 
lining and the remarkable development of the muscles. (3) Their 
position is also explained by this assumption, for a valve between the 
colon and rectum would serve to retain the food in the absorptive 
portions of the digestive tract till all nutriment was extracted, and 
then the combined action of the spines and muscles would pass the 
remainder on. 
If these views are correct, we find the primitive valvular functions 
of the rectal glands in those insects which have retained their primitive 
food-habits, while they become vestigial, or are converted to other 
purposes in the more highly differentiated forms. 
On Secreting Organs and Secretion of Wax in Bees.* — M. G. 
Carlet attempts a more definite account than has yet been given of the 
secretory apparatus and the secretion of wax in the bee. He comes to 
the conclusion that the wax is produced by the four last ventral arches 
of the abdomen ; it is not secreted, as has been supposed, by the 
cuticular layer of these arches or by intra-abdominal glands, but by the 
cells of an epithelial membrane which he calls the waxy membrane 
(membrane ciriere). This membrane is situated between two layers, the 
outer of which is cuticular, while the inner forms the internal invest- 
ment of the anterolateral part of the ventral arch. The waxy substance 
traverses the cuticular layer and accumulates against its outer face, 
where it forms a layer of wax, which is covered by the ventral arch in 
front. Hitherto this passage of wax has been supposed; it has now 
been demonstrated. 
Ecdysis and Metamorphosis of Acrididee.f — M. J. Kunckel 
d’Herculais states that the egg-case of young AcrididsB is closed by an 
operculum admirably adapted for its purpose ; this lid is raised by 
means of a cervical ampulla, and the same organ is of use in enabling 
these insects to overturn any obstacles which prevent their emergence. 
Moreover, it enables them to modify at will the various regions of their 
body, and so to escape through very small orifices. Yet, again, it is by 
means of this ampulla that they burst the envelope which incloses 
them. Freed from this, the young Acrididge are able to make use of their 
limbs, and have the use of their antennse and mouth-organs. At each 
successive ecdysis the membrane which unites the head and the thorax is 
capable of distension and of acting as a cervical ampulla ; this distension 
is effected by the region becoming gorged with blood. The ampulla in 
question may, therefore, be compared to the frontal ampulla of the 
Muscidse, but it has more extensive uses as it is of service when the young 
is still inclosed in the egg. 
In a succeeding paper J the author discusses the function of air in 
the mechanism of escape from the egg-case, and in the ecdysis and 
metamorphosis of the Acrididae. He finds that, at all stages of develop- 
ment, these insects diminish the capacity of their general cavity by 
swallowing air into the digestive tract ; by this means the air is driven 
into the cervical ampulla or into various regions of the body, and 
especially the elytra and wings. 
* Comptes Rendus, cx. (1890) pp. 361-3. f T. c., pp. 657-9. J T. c., jip. 807-9. 
1890. 2 A 
