308 Ainials Entomological Society of America [\o\. Ill, 



Plate XLVII. 



30. Transverse section through the ileum just cephalad of the ileal valve. 



.31. Longitudinal section through the ileal valve. 



.T2. Transver.sc section through ileum, caudad of the ileal valve. 



33. Longitudinal section through the valve between the ileum and colon. 



34. Transverse section through the valve between the ileum and colon. 



35. Transverse section through the colon. 



30. Portion of longitudinal section through the colon. 



37. Transverse section through the rectum. 



38. Longitudinal section through the rectum and anal papillae. 



XLVIIL 



Epithelial secretion and regeneration (with 1-12 immersion.) 



39. Epithelial cells of the mid-intestine of a larva after a four days' fast. 



40. (a) Epithelial cells of the mid-intestine of a larva after a seven days' 

 fast, (b) Same after feeding half an hour. 



41. Epithelial cells of mid-intestine of a larva that had fasted two days 

 then fed for half an hour. 



42. A single large polygonal digestive cell from the anterior portion of the 

 mid-intestine. 



43. Tall slender epithelial cells discharging digestive proliferations. 



44. Same, from region slightly cephalad of (43). 



45. Epithelial cells from the posterior region of the mid-intestine discharging 

 globules of digestive secretion. 



46. Mucus cells from posterior region of mid-intestines. 



47. Longitudinal section through the caecal gland. 



48. Epithelial cells from the anterior portion of the mid-intestine shortly 

 before molting, showing the first stage of epithelial degeneration. 



49. Epithelial cells showing a later stage of degeneration. 



50. Epithelial cells from anterior portion of mid-intestine showing the process 

 of degeneration well under way. 



51. Epithelial cells from the same larva, but from the region of tall slender 

 cells with degeneration almost complete. 



52. Newly regenerated epithelium of the mid-intestine of a larva that had 

 just emerged from the larval skin. 



53. Epithelium of the mid-intestine of a larva that had molted less than a day 

 previous to killing. 



54. Embryonic cells in various stages of development. 



