RESEARCH ON THE DIGESTIVE SYSTEM OF THE SCHIZOPODA 45 



In our section a small canal is seen leaving the centre of the sphère. 

 The spherical bodies are surrounded by the propria of Leydig, the 

 nuclei of which hâve a flattened aspect. 



Digestive glands. 



The ordinary secreting cells are conical, fig. 45. 



The larger cells are distended by large vacuoles and project a considé- 

 rable distance into the lumen, their contents are emptied into the lumen 

 of the tube by the bursting of the cells. 



The cells présent considérable différences in size ; the smaller cells 

 are cldsely packed together by the increase in size of the cells that are 

 about to excrète. 



The cells hâve a very fine protoplasmic network, that is easily seen 

 when coloured by the haematoxylin of Heidenhain, fig. 45, 46, 49. 



The protoplasm contains small vacuoles in the part of the cell that is 

 above the nucleus. 



The nucleus is situated near the base of the cells. 



The chromosomes are very deeply coloured by the basic dyes. 



The cells possess a plateau of considérable thickness with vertical 

 striations, fig. 49, and of a chitinous nature. 



In each tube several large cells are seen containing large vacuoles sur- 

 rounded by a very thin membrane, fig. 45. 49, vc. 



Near thèse vacuoles and sometimes in their interior a granular mass 

 is often found which is very deeply coloured by the hgematoxylin of 

 Heidenhain. 



Thèse granular masses are composed of proteid matter. 



Very often near the large vacuoles, smaller ones are found containing 

 isolated granules of the same nature, fig. 49. 



The vacuoles are emptied by a breaking of the cell membrane, when 

 the tension of the secreted matter becomes too great. 



The cell then appears as a shrunken mass, fig. 46. 



The ordinary secreting cells of Siriella are of a somewhat différent 

 aspect. They are columnar and disposed in masses of différent size, 

 fig. 48, 51. 



The smaller cells are found at the extremities of thèse masses; the 

 larger at the centre. 



