26 



THE VENOM OF HELODERMA. 



finally become the typical secretion granules. The latter, when fully formed, 

 become detached from the reticulum and come to lie in the vacuoles. Some of 

 the cells in fig. 10 show the early phases in the formation of the granules. In 

 no case have I seen any distinct trace of filar structures within the cells, such as 

 have been described by a number of authors in the gland-cells of the parotid, 

 pancreas, etc. 



In the process of secretion the inner membrane, facing the tubule lumen, 

 bursts, and the secretion is extruded. Whether the granules are extruded 

 bodily or whether they first undergo liquefaction previous to extrusion are 

 questions which my material does not enable me to answer. I have frequently 

 observed large, swollen, vesicle-like bodies and irregular, solid particles in the 



FIG. 11. Portion of epithelium of central duct at a point where an intralobular duct opens into it. The sections show 

 sudden change in histological character in passing from one structure to the other. Note minutely 

 granulose character of central duct cells and clear alveolar character of intralobular duct cells. Compare 

 granules of central duct cells with typical secretion granules of intralobular ducts by comparing this figure 

 with fig. 10. 



gland lumen close to the ruptured inner wall of a cell, but whether these were 

 normal appearances or artifacts due to manipulation of the excised gland pre- 

 vious to fixation I am unable to say. By whatever means the granules are 

 liquefied or dissolved, they doubtless disappear as distinct structures at the 

 time that the secretion is extruded. 



A number of authors, who hold to the view that the granules are dissolved 

 within the cell, believe that the vacuoles represent the dissolved granules. 

 These authors maintain the reticular theory of cytoplasmic structures, accord- 

 ing to which the spongioplasmic reticulum is composed of anastomosing 

 threads, instead of the more viscid covering of the vacuoles postulated by the 



