sao nee ee 
TILE ANNALS 
AND 
MAGAZINE OF NATURAL HISTORY. 
[THIRD SERIES.] 
- No. 50, FEBRUARY 1862. 
XII.—Anatomico-physiological Investigations on the Respiratory 
Process in Insects, By H. Ratnxe*. 
I. Perrect Insects. 
§ 1. Rozsat, in the second volume of his ‘ Insekten-Belusti- 
gungen,’ has noticed that in Aschna grandis the abdomen is 
alternately expanded and contracted, and that this movement is 
Snccted with the respiratory process. Carus subsequently 
made the same observation on Locusta verrucivora. These as- 
sertions led Rathke, in 1831, to examine all the larger insects 
which he could procure in the vicinity of Dorpat, to see whether 
they exhibited these movements of the abdomen. He found that, 
in the majority of insects which he could obtain for examination, 
the abdomen is alternately expanded and contracted ; and fully 
convinced himself that in Cetonia and Scarabeus this movement 
has an effect upon the respiration. 
§ 2. In all insects in which such movements of the abdomen 
may be distinctly perceived, these are not of the same kind, but 
in different insects they present many differences. These differ- 
ences depend upon the peculiar organization of the wall of the 
abdomen. But whatever may be the kind of movement, it is 
always caused and rendered possible,—1, by the epidermis of the 
abdomen being solid and thick in some parts and soft and thin 
in others, so that those parts of the cutis on which the epidermis 
forms plates or bands of greater or less thickness may be pushed 
closer together and then again somewhat removed from each other; 
and 2, by the presence of peculiar muscles on the inner sur- 
face of the cutis of the abdomen, passing from one part of the 
cutis to the other, and capable of effecting a movement in it. 
* This posthumous memoir, prepared by Rathke in 1835, has just been 
published by Dr. Hagen in the ‘Schriften der Konigl. physik. Gkonom. 
Gesellschaft zu Konigsberg,’ Ist year (1861), p. 99. Translated by W, S. 
Dallas, F.L,S. 
Am. & Mag. N, Hist. Ser. 3. Vol, ix. 6 
