1884.} Pulsating Organs in the Legs of Certain Hemiptera. 13 
OBSERVATIONS ON THE PULSATING ORGANS IN 
THE LEGS OF CERTAIN HEMIPTERA! 
BY WM. A. LOCY. 
AEAN opinions have been held regarding the pul- 
sating organs that have, from time to time, been observed in 
the legs of certain Hemiptera. 
They were first drawn and described by Behn, in 1835. These 
observations were at once called into question by Léon Dufour, 
who at that time was the acknowledged autocrat of the anatomy 
of the Hemiptera. 
Dufour considered that these movements were due to contrac- 
tions of the ordinary muscles of the legs and denied the existence ` 
of the blood currents observed by Behn. The scientific value of 
Dufour’s opinion on this point loses its force on account of his 
well known hostility to the theory of circylation of the blood in 
the Insecta. 
In the summer of 1883, while working on the circulation of 
blood in the Hemiptera, these organs came under my notice, and 
the following is a simple record of observations made to deter- 
mine: 
(1) Whether these organs are distinct from the muscular sys- 
tem of the legs, and 
(2) Whether they influence circulation ? 
To both of these questions the evidence is for an affirmative 
answer. During the progress of the work their automaticity was 
also observed and well established. 
Methods.—Different genera of the aquatic Hemiptera were fas- 
tened upon a microscope slide, their legs spread out in glycerine 
and covered with a cover-glass. The legs thus prepared were 
studied with both low and high powers of the microscope. Speci- 
mens for examination were chosen with reference to the trans- 
parency of their legs, as it is upon this point that success of ob- 
servation depends. Both larval and adult forms of the genera 
Studied were used, but the best results were uniformly obtained 
with the larval forms, on account of the greater transparency of 
their legs. 
In some cases special methods were necessary to render the 
legs transparent enough for observation. For this purpose the 
1 Work from the Biological Laboratory of Mt. Morris College, Mt. Morris, Illinois. 
: è 
