698 : LAavuRA FLORENCE 
sizes, the largest being peripheral in position. Both in cells stained with 
hematoxylin and eosin and in those stained with iron hematoxylin, the 
groundwork appears to be alveolar with many dark-staining granules 
adhering to the walls of the alveoli. When they are stained with iron 
hematoxylin and the differentiation with the iron-alum solution is not 
carried far, it is impossible to distinguish the fat from the other granules; 
but if the destaining is carried further than is customary, the fat retains 
its black color, while the other granules become a grayish brown. 
In living specimens the distribution of the fat body is clearly seen 
shining through the integument, and in mature specimens there may be 
seen in the abdomen many green cells scattered among the white fat 
cells. In his description of the fat body of Phthirius, Landois (1864:11) 
mentioned emerald green cells which stood out with greatest clearness 
in the lateral region of the abdomen of adult males, but he did not refer 
to such cells in his later work on the two species of Pediculus. Graber 
(1872:152) also described, in Phthirius, cells with a greenish, transparent, 
viscous content and usually with two distinct nuclei. In Lznognathus 
vituli (Haematopinus tenuirostris) Strébelt (1882, English trans. 1883:90) 
found that ‘‘ a fine and delicate membrane envelops the yellowish green, 
finely granular contents, which readily allow two nuclei to be recognized,” 
while in the abdomen he saw small, globular cells with darker-colored 
contents. Nuttall (1918:378) has also mentioned these green cells as 
appearing in Phthirius when the insect attains sexual maturity. He 
criticizes the statement of Oppenheim (1901) that the pigment is formed 
by a ferment in the salivary glands and is deposited in the insect’s fat- 
body, and states that the significance of the pigment is yet to be deter- 
mined. In sections through mature lice these ceils are found lying 
among the fat cells in the lateral regions of the abdomen. They are 
much smaller than the fat cells, and have, as a rule, only one nucleus 
with a well-defined nucleolus, although two nuclei have sometimes been 
seen. Their cytoplasm is filled with granules which stain a neutral tint 
as compared with the positive tint taken by the granules in the fat cells. 
The structure and position of these green cells suggest their interpretation 
as oenocytes, or further investigation may prove them to be disseminated 
nephrocytes such as Nuttall and Keilin (1921:184) have just described 
in Pediculus. 
