528 ON THE INTERNAL ANATOMY OF BDELLA. 



Fig. 35. Sectiou througli the testes and embedding-sac on one side of the hody : x60; showing that the 

 latter is a hollow visciis, although the lumen is small in comparison to the size of the organ 

 The sperm-mother-cells are seen on the right part of the testes, the portion functioning as a 

 vesicula seminis on the left nearest to the embeddiug-sac ; these portions are full of 

 spermatozoa. 



36. Median sagittal section througli the mucous glaud (vas deferens?) and glandular antechamber 



on one side of the body : x 100. The cells have all di?charged their contents and are empty, 

 their walls remaining, forming pockets ; the outer fleshy walls with the nuclei persist. 



37. Section of a portion of the mucous gland when partly filled with secretion : x 140. 



38. Median sagittal section of one of the glandular antechambers of the male: x 400. 



39. Median sagittal section through the laminated gland of the male : X 150. 



40. Longitudinal section through the air-chamber of the male genital organs, to show the spines 



projecting into the interior : x 400. In this figure the lower end is slightly the anterior. 



41. Transverse section of male Bdella vulgaris cut in the plane of the glandular antechambers to 



show the difference of their cellulation from those of B. Basteri. The muscles arising from 

 the amphioid sclerite are inserted into the labia which close the ducts from the azygous 

 accessory and laminated glands; just the end of the last-named gland is seen above the 

 labia. The inner portion of the mucous gland on the right side is shown just at its end, 

 where the minute passage from the testes exists ; this is shown by the small circle in the 

 middle of the light spot ; the other parts of the mucous glands are cut a little deeper in the 

 wall of that organ. 



42. Transverse section of male Bdella vulgaris posterior to fig. 41 and taken in about the central 



plane of the peuial canal (the head of the canal bends over in this species). The small part 

 of the azygous accessory gland is seen cut through transversely immediately above the 

 penial canal. 



43. Transverse section of female in the plane of the receptaculum seminis : x 30. The oviduct is 



distended by eggs, some nearly I'ipe for discharge. The cells of the cseca of the ventriculus 

 are full of food-droplets. The walls of the oviduct have become very thin in consequence 

 of the distension 



44. Section through part of the wall of the oviduct of a young female: x2o0; showing the 



thickness of the wall, the mode of folding, and the cellulation. 



45. The respiratory organs : x 65. The Avhole of the air-chambers and principal tracheal trunk are 



shown, but the finer tracheae are cut short. 



