The Hog Louse 695 



(1890:246) in the larva of Ptychoptera contaminata. The epitheHal 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 tiorder 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 

 examination revcaleil 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 twent,y-four hours. After sectioning, some were mounted unstained 

 and others were stained with safranin. Absorption evidently began 

 almost inmiediately, for at the end of one hour a few deep Ijlack granules 

 were found just beneath the Ijortler of the cells of the anterior region of 

 the stomach. As the series was aseendetl, the black granules increased 

 greatlj' in number and in size. The largest lay just mider the border 

 of the cell, and their size was in inverse ratio to the ilegree 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 Uning 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 waj' and the secretion was in process of lieing 

 excreted. In the louse killed at seven hours, absorption was proceeding. 



