46 Charles GELDERD 



Amongst the latter there are one or two in each préparation con- 

 siderably developed and projecting into the lumen of the tube, fig. 51. 



The internai extremit}^ has lost its cylindrical form and has a rounded- 

 ofîf aspect. 



The nuclei of thèse cells instead of being situated towards the base of 

 the cells, hâve taken up their position in the raised portion. 



The protoplasm of the ordinary cells has a filamentous aspect very 

 clearly marked. 



In the projecting cell the protoplasm has a filamentous aspect and is 

 clearer in the external portion; it is granular, on the contrary, and dark in 

 the internai portion. 



The nuclei of the projecting cells are a little larger and seem to be 

 richer in chromatin than the others. The cells are covered by a thin mem- 

 bran. They are eventually cast off into the lumen of the tube as globular 

 bodies containing the nucleus. 



The tubes of the digestive glands possess a serons membrane, the 

 propria of Leydig; 



Glaudiilar ridges in the tubes of the digestive gland. 



They consist of a simple layer of columnar cells, fig. 45, 46, 48, 50. 



This curions formation makes its appearance in the terminal portion 

 of the tubes. 



We hâve already indicated where they are found. 



If we section one of the long tubes at the extremity, certain cells 

 become differenciated and become gradually longer, as we foUow the section 

 forwards, forming a semi-circular mass ; the smaller cells being found at the 

 extremities, the larger at the centre of the mass, fig. 45, 46, fg. 



The horizontal aspect of thèse masses shows that their contour has 

 often an undulated appearance, caused by variations in the length of the 

 component cells, fig. 46. 



The protoplasm of the cells appears to be composed of fibrils, fig. 50. 



The nuclei are very large and elongated, formed of small chromosomes 

 which stain very deeply with the basic dyes. 



The nuclei are found close to the superficial portion of the cells at the 

 beginning of the formation of the vacuoles. 



The vacuolisation becomcs more complète as we advance towards the 



