314 PROCEEDINGS OF THE ACADEMY OF [Apr., 



(HypS). This indicates that the sense cells are modified hypodermal 

 cells. It appears that the cone iCon) is formed after ,the surrounding 

 chitin is almost completed. In figure 38 the hypodermis (Hyp) has 

 shrunk a short distance from the chitin {Ch) drawing the hypodermal 

 strand (HypSt) an equal distance from the base of the cone (Con). 

 This strand probably served as a passage-way for conveying a 

 hypodermal secretion which formed the cone. With Ehrlich's 

 hamatoxylin and oesin the outer margin (a) of the cone stains a 

 faint purple. The inner margin (6) is pink, having the same color 

 as that of the lowest strata (c) of the surrounding chitin. The 

 chitin at d is light yellow; at e, dark yellow, and at /, it is semi- 

 transparent. At these last three places it failed to stain. 



Judging from what can be gleaned from all the sections studied, 

 including those of the honey bee, the origin of these organs is probably 

 about as follows. In the early pupal stage, the hypodermis is thick, 

 no chitin is yet formed, and all the hypodermal cells have about the 

 same size. In the 16-day-olcl worker pupae of the honey bee neither 

 pores nor sense cells are found, but many large hypodermal cells 

 occur where the sense cells later appear. At this age the chitin and 

 hairs are being rapidly formed. A day later pores and sense cells 

 are found. The sense cells and flasks including the pore apertures 

 are then simultaneously formed, while the cone and sense fiber are 

 later formations. Both poles of the sense cell are formed as growing 

 processes. The peripheral pole unites with the pore aperture and 

 the inner one joins the nerve branch while the cone is being formed 

 by the hypodermal strand. 



The flasks vary much in diameter and length. The length always 

 depends on the thickness of the chitin. Figures 6 and 7 represent 

 the largest and smallest pores in the tibiae of the pupal females of 

 Formica. Figures 8 to 11 represent the flasks as found in the wings 

 of the same insect. Figure 8 is from group No. 2, and figure 9 is 

 from group No. 3 on the front wing. Figure 10 is from group No. 4, 

 and figure 11 is from group No. 5 on the hind wing. Figure 12 from 

 group No. 2 on the front wing shows the slight variations in size 

 of the flasks and also the bunch of sense cells (SC). Here none of 

 the pore apertures were discernible. Figures 13 and 14 show how the 

 pores, sense cells (SC), and hypodermis (Hyp) actually appear in 

 sections through the trochanters of the same insect. Figure 13 is 

 from group No. 7 and figure 14 is from group No. 8. Quite often 

 the sense cells (fig. 14, SC) lie among the hypodermal cells (HypS), 

 and hypodermal strands (HypSt) may be seen running toward and 



