1916] Reflex " Bleeding'' of Epilachna 207 



(?) Origin of hypodermal glands with reservoirs. 



In regard to the formation of the reservoirs and efferent 

 tubes nothing can be said, because they are fully developed 

 when the insect emerges, and no younger stages were preserved 

 in fixing fluids. 



When the insect has been emerged an hour, the chitin is 

 about one-third developed. This is seen by comparing Figures 

 11 and 13. Figure 11 is from an old adult, and Figure 13 is from 

 a beetle emerged one hour. The darker-colored chitin (Figs. 

 10 and 11, chi) is formed before the insect emerges and the 

 lighter-colored chitin {chi) is formed after the beetle emerges. 



When the insect has been emerged an hour, the gland cells 

 vary in development from undifferentiated hypodermal cells to 

 almost fully developed gland cells. At this stage the hypo- 

 dermis (Fig. 13, h) is comparatively thick and the hypodermal 

 cells {he) appear as dark-staining nuclei without the cell walls 

 being visible. The first stage in the formation of a gland cell 

 may be represented by a large hypodermal cell at the mouth of 

 a reservoir (Fig. 13, he). The second stage is represented by 

 a hypodermal cell that has enlarged sufficiently to cause the 

 hypodermal wall to bulge outward. Its nucleus is now com- 

 paratively light in color, its cell wall is discernible, and its 

 cytoplasm is darker than that of the hypodermis. Figure 14, 

 glc, represents such a stage. 



The third stage in the development is represented by a gland 

 cell that is forming the conducting tube. All the steps during 

 the formation of the conducting tube were not seen, but enough 

 were observed to imagine the full procedure in the development. 

 A gland cell in the second stage of development is round, or 

 slightly oblong. Now it begins to elongate rapidly and one 

 end begins sending out a process. At this step the ampulla 

 appears and the free end of the conducting tube is formed. The 

 conducting tube is formed from the cellular secretion as rapidly 

 as the process of the cell grows in length. Since the tube at 

 this step often appears as a single dark heavy line instead of two 

 parallel lines, it is probably laid down as a rod of secreted sub- 

 stance rather than as a tube, but later it becomes cylindrical. 

 Gland cells with processes {pr) of various lengths are shown in 

 Figures 15 to 17. One process {pr) shown in Figure 17 has 

 actually entered the mouth of a reservoir. Now it may be 



