SEA-FISHERIES LABORATORY. 429 



In sections through the antennary gland the 

 following structures may, therefore, be made out: — 



Dorsal, (a) The main portion of the end sac. This 

 is a simple cavity lined by squamous epithelium, the cells 

 of which do not take the stain well. 



Ventral. The labyrinth made up of the following 

 parts : — 



(b) Numerous small spaces with an inner lining of 



squamous epithelium (ventral prolongation of the 

 end sac), and an outer lining of deeply stained 

 columnar epithelium. 



(c) Irregular spaces surrounded by columnar epithelium 



which is deeply stained. On the side facing the 

 lumen the cells are lined by a fine border. These 

 are portions of the renal tube. 



(d) Small spaces lined by the renal tube epithelium. 

 In the spaces are connective tissue cells and blood. 

 These are the trabecular ingrowths. In some parts 

 the epithelium of the trabeculae fuses with the 

 epithelium of the roof of the renal tube, so that 

 the blood sinus passes right through the labyrinth. 



(e) Between the epithelium of (b) and (c) may be made 



out small blood sinuses. 

 (2) The bladder (Fig. 57, Text figs. 11, 12) is 

 extensive and complicated. It is a thin-walled sac 

 readily made out on account of its deep brown colour. 



The Main Yesicle is situated above the antennary 

 gland, and its cavity is continuous with that of the renal 

 tube at the inner and posterior end of the antennary 

 gland In front of the gland it is connected with the 

 ureter. From the main vesicle are given off the follow- 

 ing lobes : — 



(a) at the anterior end — Epigastric lobe, Progastric 

 lobe, Antero-lateral lobe, Cerebral lobe. 



