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pupal barrel-like envelope from the chitin skin of the larva, the 
imaginal disks develop themselves into the head and thorax. There 
is a destruction of all the organic systems, which are re-formed at the 
expense of the fat body. ‘The genital glands are present in the 
embryo, and develop themselves gradually. The pupa condition is 
protracted, and the insect is inactive. 
It is remarkable that even in the same Order such great differences 
in development should occur. Similar cases, however, are well 
known in other parts of the animal kingdom. 
he principal difference between Corethra and Musca resides in 
thé imaginal disks, and Dr. Weissmann proposes therefore to divide 
the metabolic insects into two divisious, ‘* Adiscota ” 
intermediate stages are to be met with. 
The same journal contains a short paper by M. Mecznikow, on _ 
the Embryology of Hemiptera, and a memoir by M. W. Brasius, on ~ 
the loss of weight of Lepidoptera during the change from the larva 
to the imago. 
Dr. C. Kupfer has published a short memoir on the early stages of 
development in Chironomus, as to which he does not altogether agree 
with the views of Weissmann. 
M. Hensen* has published a memoir on the auditory organ of 
Locusta, in which he confirms the description given by Von Siebold. 
He also endeavours to prove that there is an identity of plan between 
this organ and the ear of Crustacea, comparing the auditory rods of 
the former with the hairs of the latter. He admits that the rods have 
at their apex a large cell, of which the hairs show no trace; but he 
argues that the rods of Locusta are primary structures, while the 
and “ Discota.” 
He admits, however, that between these two extremes all possible © 
{ 
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auditory hairs of Crustacea have never been examined until after | 
several changes of skin; and he thinks that if the auditory hairs were 
examined before the first moult, corresponding cells might probably 
be found at their apex. In any case he does vot think that the mere 
presence of these cells is sufficient to destroy the analogy. 
He concludes therefore that these auditory rods, like the auditory | 
hairs of Crustacea, are thrown into vibration, when they are fitted, by | | 
* Zeits. f. Wiss. Zool. Vol. xvi. Pt. 2. 
