ANATOMY OF THE POISON GLAND OF HELODERMA. 



27 



alveolar theory. The poison gland of Helodertna is not a suitable object for 

 testing the validity of the various protoplasmic structure theories, but I have 

 chosen to interpret the facts in conformity with the alveolar theory, since on 

 general grounds that appears to me to have most in its favor. The vacuoles 

 appear to me to be always present, although in the empty gland-cells they are 

 frequently quite minute, owing apparently to the shrinkage of the cells and the 

 consequent condensation of its cytoplasm. They are present and of full size 

 in many cells in which the early stages of granule formation, as evidenced by 

 the presence of the minute particles in the nodes of the reticulum, were alone 

 visible. I am inclined, therefore, to view the vacuoles as relatively constant 



Fig. 12. — Section through part of single lobule of po son gland showing terminal aeiiu tZeissoc 4 obj 3mm ap.0.95). 



constituents of the cell protoplasm. Whether at the moment of secretion the 

 granules dissolve in the liquid of the vacuoles, or are instead extruded into the 

 gland lumen, where they quickly dissolve, can not be settled by the material 

 examined. 



The outer or basal portions of the granule-forming cells are filled by a 

 relatively dense, homogeneous cytoplasm, similar to that which nearly all 

 authors have described for that portion of the gland-cell. The protoplasm 

 appears to be alveolar, but the vacules are extremely minute and closely 

 crowded together. The nucleus is embedded in this cytoplasm. 



The nucleus of the gland-cells is tjTjically quite large and conspicuous, and, 

 as already mentioned, is embedded in and surrounded by a relatively dense 



