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Development of the Embryo in the Egg of Toxoptera graminum. 

 Fig. 1. — Sagittal section of the embryo showing the segmentation. The invagination of the salivary glands is now evident. The fundaments of the ovaries have assumed more 

 definite shape and have shifted in position. The ovarian yolk is greatly changed in appearance and has taken up a position at the anterior port ion of the abdominal region. 

 The "polar organ" now shows a large, somen luu pear-shaped central cavity which opens upon the surface of the egg and is filled with a yellowish substance. Magnified 156 

 diameters. Fig. 2.— Sagittal section ( slight Iv oblique I showing a much more advanced stage of growth than that of figure 1, the abdominal region having reversed its posi- 

 tion by bending around backward and inclosing the ovarian yolk. The mesenteron is in process of formation. The ovarian yolk is granular and its cells are breaking clown. 

 The "polar organ " is much the same as in the preceding stage. Magnified lfli diameters. (Original.) 



