182 PROF. W. H. JACKSON ON THE 



amount of clear non-staining substance between the cells. Compared with fig. 32, which is 

 magnified to the same degree, it is at once evident that the cells are smaller in diameter. 

 Obj. D, oc. 2, Zeiss, draw-tube in. 



Fig. 48. Vertical section of hypodermis from the seventh segment of the same specimen. The cells are 

 elongated and close set ; their nuclei are nearer their outer than their inner ends. The inter- 

 cellular substance is visible. There is a thin basement-membrane, 6, and a very delicate pupal 

 cuticle, cu. The latter is partly seen from the surface. Obj. D, oc. 2, Zeiss, draw-tube in. 



Fig. 49. A similar preparation, similarly magnified, from the cremaster of a one day old pupa. The 

 nuclei are at the inner ends of the cells. 



The six following figures are taken from an active full-grown caterpillar, still feeding, with paired vesicles, 

 in the stage represented fig. 33, PI. XVIL, and are all drawn under obj. B, oc. 2, Zeiss, draw-tube in. 



Figs. 50 a to 50 d. Transverse sections from the anterior paired vesicle. 



50 a. From the anterior end, second section of the series ; the median furrow is seen in the centre. 

 50 b. The next following section ; the median furrow is deeper. 



50 c. The sixth section of the series ; x , the lateral fold which is the first indication of the forming 

 middle section of the azygos oviduct. 



50 d. The next following or seventh section ; x , the same fold, which is rather deeper. The left side 



of this section is partly broken and bent, therefore dotted in. Three more sections, which 

 closely resemble 50 a, end the series. 

 Figs. 51a and 51 b. Transverse sections from the posterior paired vesicle of the same specimen. 



51 a. The first section from the anterior end. 



51 b. The sixth section of the series ; /, one of the filaments. This section seems to me slightly 



oblique to the long axis. The five following sections are very similar, but diminish gradually 

 in size. 



PlATE XVIII. 



All the sections in this Plate are drawn to the same scale as figs. 50 and 51 in the preceding Plate, i. e. 

 under obj. B, oc. 2, Zeiss, draw-tube in. 



Figs. 52 a to 52 c. Transverse sections of the anterior paired vesicle of a caterpillar ceasing to feed and 

 about to suspend itself. 



52 a. The fourth section from the anterior end ; x , the lateral fold to form the middle section of 



the azygos oviduct. The median furrow is still visible. 

 52 b. The seventh section ; x , the lateral fold is of large size, and the basal aperture is somewhat 

 narrowed. The three following sections are similar but larger, and the series then diminishes 

 in size. 



52 c. The thirteenth section ; there is no trace of a median furrow. One more section similar, but 



much smaller, ends the series. 

 Figs. 53 a to 53 d. Transverse sections from the posterior paired vesicle of the same specimen. 



53 a. The first section of the series. 



53 6. The third section of the series ; the median furrow is very distinct. The next section is 



similar and larger. 

 53 c. The fifth section of the series ; a portion of the roof of the vesicle on the left side is cut 



obliquely. 

 53 d. The eighth section of the series ; /, one of the filaments ; m, the portion of the roof of the 



vesicle coinciding with the dotted line is converted into the sebaceous apparatus of the adult. 



Compare figs. 54 ff to 54 k following. The rest of the vesicle forms apparently the posterior 



end of the oviduct. 



