Tue Hoa Louse. 695 
(1890: 246) in the larva of Ptychoptera contaminata. 'The epithelial cells 
are bounded on their free edges by a border, which appears in most cases 
to be definitely striated. 
- Taken from its host and confined without food, the hog louse is a short- 
lived insect, and starved specimens invariably died in from twenty-eight 
to thirty hours after their last feeding. In lice killed, respectively, seven- 
teen and twenty-four hours after feeding, and sectioned, the stomach was 
found empty of food, its walls contracted, and the majority of the cells 
swollen with secretion while in some cases the border of the cell was 
ruptured and the ball of secretion had escaped into the lumen. This 
would suggest that hunger stimulates the activity of the secreting cells, 
and also the liberation of their products into the lumen. 
From a louse fed two hours previously, the stomach was dissected out 
in physiological salt solution and a part of the wall teased. Microscopic 
examinaticn revealed the presence within the cells of two types of granules, 
of which the more numerous were fine, irregular-elongated, and dark, and 
the less numerous were coarse, round, and refractive. A 2-per-cent 
solution of osmic acid was then introduced under the cover glass, and the 
coarse granules turned black, showing them to be either lipoid or proteid, 
while the fine ones probably represented secreting granules. A _ series 
of twelve lice were killed with chloroform at intervals of one hour and the 
stomachs immediately dissected out in a mixture of equal parts of 2-per- 
cent osmic acid and salt solution and fixed in Flemming’s weak solution 
for twenty-four hours. After sectioning, some were mounted unstained 
and others were stained with safranin. Absorption evidently began 
almost immediately, for at the end of one hour a few deep black granules 
were found just beneath the border of the cells of the anterior region of 
the stomach. As the series was ascended, the black granules increased 
greatly in number and in size. The largest lay just under the border 
of the cell, and their size was in inverse ratio to the degree of penetration 
within the cell. In the first six of the series a definite increasing absorption: 
could be traced in the bulk of the cells lining the wide section of the 
stomach, and this absorption was going on even in cells forming secretion. 
In the latter the black granules lay in a circle outside the zone of secretion, 
and were never seen to come in contact with it even in the few cases in 
which the border had given way and the secretion was in process of being 
excreted. In the louse killed at seven hours, absorption was proceeding, 
