THE ALIMENTARY SYSTEM. 
33 
SALIVARY GLANDS. 
These organs are not of uncommon occurrence 
amongst the Hemiptera Homoptera, and are almost 
always of a simple character. Leon Dufour shows by a 
figure that they are distinct and well developed in 
Cicada, but states that he could find no trace of them in 
either Psylla or Aphis. He admits, however, that his 
microscope was hardly adequate in magnifying power 
to examine this latter family. The internal tissues of 
Aphides are of extreme tenuity and transparence. 
They break up on very slight pressure, and therefore 
it is desirable to dissolve sugar or common salt in 
those fluids which are employed for dissection. 
In those specimens of Aphides in which I have 
detected salivary glands, they appear as rounded 
pyriform bodies, situated in the immediate vicinity of 
the base of the rostrum, and partly filling the cavity of 
the thorax. 
These masses consist of bundles of delicate vessels 
ranged side by side into distinct lobes. Morren 
noticed like appendages to the head of the Aphis he 
describes as Aphis per sicce, 
HEPATIC VESSELS. 
Although Leon Dufour^ failed in detecting any biliary 
vessels in Aphides, I believe that in some genera they 
exist. In Amy da I have seen a kind of beaded chain 
attached to the lower end of the alimentary canal, 
which, from its position, I should conclude belonged to 
the hepatic system. 
In Psylla the alimentary system is more complicated 
than in Aphis. The stomach has the oesophageal and 
* Leon Dufour, ‘ RecRerclies Anatomiques et Physiologiques sur les 
Hemipteres,’ p. 118, et seq. This author says the minute size of Aphides 
should be no bar to discovering the hepatic organs, if they existed. 
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