INTERNAL GENERA TIVE ORGANS OF THE FEMALE. 673 



which have usually been regarded as colleterial or glue glands.* 

 There are a single pair which open into the sacculus of the 

 oviduct by a pair of ducts. These glands lie one on either side 

 of the oviduct, embedded in adipose tissue, and each extends 

 along the outside of the corresponding tuba, and terminates in 

 a csecal extremity which is attached to the ovary. They are 

 white, with a pearly lustre, and exhibit a beaded appearance 

 due to the projection of the outer surfaces of the cells which 

 line them. 



In sections they exhibit a peritoneal coat, and consist ot 

 a structureless basement membrane, lined by a single layer of 

 large epithelial cells. The lumen of the gland is occupied by 

 a granular fluid or semi-fluid substance of a highly coagulable 

 character. The granules suspended in this fluid are intensely 

 blackened by osmium peroxide. 



The general structure of these glands is similar to that of 

 the vas deferens and paragonia of the male ; but the epithelial 

 elements are much larger, and are irregular in form ; the cells 

 measure on an average 80 p, in diameter, and are from 30 yu, to 

 40 /i thick. 



Many of these cells contain very remarkable spherical cor- 

 puscles, usually one in each cell. The corpuscles bear a striking 

 resemblance to the ova of many Mammalia ; they exhibit a 

 zona pellucida with distinct radial strias, enclosing a granular 

 protoplasm, which exhibits a vesicular nucleus with a minute 

 highly refractive particle in its interior comparable with the 

 well-known germinal spot (Fig. 94). 



Beside these corpuscles, many of the cells also exhibit an 

 oblong nucleus, surrounded by a clear area. 



The largest of the contained corpuscles measure 25 yu. to 



* Colleterial or glue glands are glands which open into the posterior part of the 

 genital canal, close to the external orifice, and secrete a viscid fluid by which the 

 eggs are varnished or attached to each other, or to leaves, branches, etc. Such glands 

 are found largely developed in the Lepidoptera, and resemble the sericterial or silk 

 glands in structure and in the nature of their secretion. There are no colleterial 

 glands in the Blow-fly, and the cement with which the eggs are united with each 

 other when deposited is probably secreted by the walls of the utero-vaginal tube ; 

 the genital fossae are frequently found filled with a similar material, which is ap- 

 parently a coagulable albuminous fluid. 



