PAEACOKOTOCA AKERMANI (WAKKEX). 363 



still showing calyx (cy.) in the cortex. Note frontal nerve (f.n.) 

 immediately dorsal to oesophagus. 



Fig. 56. — x 170. Vertical ci'oss-section a little posterior to that of 

 fig. 55. Only the cortex of the ijosterior periphery of the procerebral 

 lobes is seen. The origin of the tritocerebrum and lateral oesophageal 

 ganglia is shown. A transverse commissure (tr. c.) running ventral to 

 the oesophagus connects the oesophageal ganglia of the two sides. The 

 roots of the frontal nerve are seen dorsal to the gut, and the labral 

 nerve (la. n.) is also seen. 



Fig. 57. — X 700. Mandibular gland in section, consisting of large 

 glandular cells, with exceptionally large nuclei and no obvious cell out- 

 lines. The secretion apparently exudes at a s^jot (d. m.) situated between 

 the mandible and maxilla 1. 



Fig. 58. — x 500. Cross-section of oesophagus in hinder region. 

 Some of the ectodermal epithelial cells (oe. ep.) are provided with long 

 spines (s2')i.) radiating to the centre and forming an efficient strainer, 

 through w^iieh passes the coarsely granular food (/'.). 



Fig. 59. — x 500. Vertical longitudinal section through the body- 

 wall and middle portion of mesenteron in a female. The cells of the 

 endoderm (e.) are of very unequal height and there are large vacuolated 

 cells. The food has become somewhat less stainable and is less coarsely 

 granular than that in the oesophagus. 



Fig. 60. — X 240. Cross-section of middle region of mesenteron of a 

 male, showing crumpled wall, vacuolated cells discharged bodily into 

 the semi-digested food, a continuous layer of substance (I. c.) (digested 

 food being absorbed?) on the inner surface of the epithelium, and a 

 number of deeply staining gland-cells wedged at the base of the 

 epithelium. The food in the lumen has become highly vacuolated, very 

 finely granular, and stains but little. 



Fig. 61. — X 500. Cross-section of anterior narrow portion of colon, 

 with large irregularly shaped ectoderm cells and no ol)vious cuticle. 



Fig. 62. — X 500. Longitudinal section of posterior portion of colon, 

 with small irregularly shaped cells, which may exhibit considerable 

 chitinisation. 



Fig. 63. — x 37. Male genital organs. The illustration was prepared 

 from a series of sketches made from a good set of serial sections. The 

 seminal ducts and ducts of the branched vesicular seminales and of 

 the unbranched accessory glands open close together at the anterior 

 end of the ejaculatory tube. 



Fig. 64.— X 650. Cross-section of a portion of the accessory gland, 

 showing an epithelium of peculiarly slender, tall cells. The thick 



