102 
Nephrocytes of Pediculus 
Summary. 
In Pediculus humanus are found two groups of excretory-accumulatory 
cells known as nephrocytes. 
The one group, the peri-oesophageal, lies ventrally and consists of large 
cells aggregated usually in two masses about the oesophagus anterior to the 
reniform salivary glands. 
The second group lies dorsally and consists of disseminated cell aggregates 
linked with the fat body. 
The typical nephrocyte is a binucleate cell with granular protoplasm con¬ 
taining greenish droplets of varying size. The excretory function of the nephro¬ 
cytes is demonstrated by intra-coelomic injection of ammonia-carmine. The 
latter, 24 hours after injection, is taken up by the nephrocytes which become 
red and filled with the carmine granules. These granules remain in the proto¬ 
plasm of the nephrocytes throughout the life of the insect. 
Similar cells exist in Mallophaga and have been wrongly described by 
some authors as salivary glands. 
The two groups of nephrocytes, described by us in Pediculus, occur in 
other insects, but the dorsal group in the latter forms usually two chains of 
cells (known as pericardial cells) lying on either side of the heart. 
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