698 Laura 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 Linognathus 

 vituli {Haeraato-pinus tenuirostris) Strobelt (1882, Enghsh trans. 1883:90) 

 found that " a fine and delicate membrane envelops the j^ellowish 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 p-nd 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 cells are found l}'lng 

 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 oenocytcs, or further investigation may prove them to be disseminated 

 nephrocytes such as Nuttall and Keilin (1921:184) have just described 

 in Pediculus. 



