70 W. BALDWIN SPENCER. 



PLATE Vin. 



List of References. 



Ace. F. Accessory gland of female. Al. Gl. Gland-cells in walls where 

 mid- and hind gut unite. Ct. Connective tissue. Cu. Sp. Cuticle lining 

 spermatheca. Cu. U. Cuticle lining uterus. E. Subcuticular epithelium. 

 H. G. Cavity of hind gut. M. G. Mid-gut. M. G. E. Epithelium of the 

 hind gut. Jfg. Muscle-band from oviduct to uterus walls. M. E. G. 

 Muscles in wall of hind gut. M. AL Muscle running forwards from anterior 

 eud of mid-gut. M. Al. Long. Longitudinal muscles of mid-gut. M. Al. Tr. 

 Circular muscles of mid-gut. M. CE. Sphincter muscle of oesophagus. M. Tr. 

 Transverse muscles. Mes. Mesentery supporting ovary. CEs. (Esophagus. 

 Od. Oviduct. Ov. Ovary. B! . Ridge in cuticle bounding opening of stigmatic 

 gland. Sp. B. Epithelium of spermatheca. Sp. D. Duct of spermatheca. 

 Sp. D. E. Epithelium of duct of spermatheca. Sp. Gl. Gland-cells of wall 

 of duct of spermatheca. Sp. M. Muscles of wall of spermatheca. St. Gl. 

 Stigmatic gland. St. Gl. 0. Opening of stigmatic gland. U. Uterus. W, 

 Special radial strands of connective tissue in the body-wall. 



EiG. 50. — Longitudinal vertical section through the opening of the oesopha- 

 gus into the mid-gut. The oesophagus is lined by columnar cells with a 

 distinct chitinous layer, the cells forming a papilla on the floor of the mid-gut 

 and dipping under the hypoblast-cells, from which they are sharply marked 

 off. The latter are thrown into folds and are columnar in form, with large 

 spherical nuclei. Where the oesophagus enters the floor of the mid-gut 

 the cavity of the former swells out into the definite form represented in the 

 figure, and immediately below this cavity is a band of circularly disposed 

 muscle-fibres. 



EiG. 51. — Longitudinal section through the body-wall in the anterior part 

 of an annulus of a mature female. The layers of circularly and longitudiually 

 disposed muscle-fibres are seen, the former consisting of hollow fibres or 

 groups of fibrils. The external cuticle is marked by lines, and immediately 

 within it lies the subcuticular epithelial layer, Masses of these cells are 

 modified to form the stigmatic glands, two of which are cut through. The 

 space immediately within the epithelial layer is occupied by connective tissue, 

 in which nuclei are irregularly scattered. 



Fig. 52.— Gland-cells. These are taken from the hook-gland of a mature 

 female, but so far as the structure of the cell itself is concerned those form- 

 ing the hook, head, and parietal glands are identical. Two small groups of 

 cells are represented, one consisting of two, the other of three cells. The 

 curious clear central space with radiating lines of granules is seen in each, 

 and in the larger one the fine duct which arises from this. Zeiss, ape, 4*0 mm., 

 0-95 apert., oc. 8. 



