192 M. LEWIS NICKERSON, 



So much may be said in the way of a general description of these 

 organs, but for a correct understanding of the individual cells and 

 intracellular structures, the various conditions presented by different 

 phases of activity must be considered. At what is probably a com- 

 paratively early stage in the activity of one of these gland cells, there 

 are present in the upper portion of the cell two membranous sacks 

 lying one within the other and separated by a considerable space. 

 This space is traversed by many delicate radiating filaments which 

 connect the walls of the two sacks. The inner sack becomes con- 

 tinuous at its outer end with a narrow canal, while the outer sack is 

 continuous with a sheath surrounding this canal. The main duct 

 resulting from the union of the several canals is in turn enveloped 

 by a broad sheath which is a continuation of the sheaths surrounding 

 the individual canals (Fig. 2). The walls of ampullœ, canals , and 

 main duct, present the appearance of homogeneous membranes staining 

 uniformly. The sheath of the main duct and its branches consists of 

 finely granular protoplasm, limited on the outside by a delicate 

 homogeneous membrane which is a direct continuation of the wall of 

 the outer ampulla. 



At the side of the main duct, near the junction of its branches, 

 is situated a large nucleus within the sheath, which broadens markedly 

 just at this point. This nucleus is surrounded by a very clear sharply 

 limited area which probably represents a vacuole. When , as is 

 frequently the case, the ampullae in the cells of one half of the organ 

 are larger and older than those of the other half, this nucleus lies 

 on the same side of the main duct as the larger ampullae. 



As already stated, the description given of the gland cells and 

 their intracellular ampullae, applies to only one of the various con- 

 ditions shown by these organs, and this condition is probably early 

 in the process of secretion. The appearances presented by different 

 organs and by different cells of the same organ vary widely, cor- 

 responding with the stage of activity. At a period in the history of 

 the cells, somewhat later probably than the one described, both inner 

 and outer sacks are much enlarged and the space between them is 

 reduced to a narrow zone. The radial filaments between the two 

 sacks are shorter and less distinct and the protoplasm of the cell now 

 much reduced in quantity by reason of the enlargement of the sacks, 

 shows large vacuoles which are in some cases confluent with the 

 outer sack. 



At a still later phase, both inner and outer walls of individual 



