ATTRACTIVE AND REPULSIVE ODORS 403 



its original diameter. The nucleus remains round and full and does 

 not deteriorate in any visible degree. When fully developed, the secre- 

 tion is in the form of closely packed granules, and the cells float free from 

 the epithelium in the loose secretion that occupies the lumen of the gland. 

 After this the granules dissolve into a fluid and the stroma of the cell 

 may rupture, setting the secretion and the nucleus free, or it may remain 

 intact for a long period, retaining the secretion and nucleus, which latter 

 has by this time lost its internal structure while yet remaining round 

 and full in outline. When the secretion is discharged, all the remaining 

 cells are probably ruptured, setting the secretion free. 



The above are the principal cells of this gland, but the secretion is 

 contributed to by another set of cells in a very small degree. This latter 

 kind is found at rare intervals in the basal layer as well as in the other 

 layer of the epithelium of the gland wall. The secretion of these cells 

 is a thick, heavy, yellow oil which is sometimes placed in a single large 

 globule, but more often appears in smaller ones. A remarkable feature 

 is that more of these cells with their golden-yellow contents are to be seen 

 outside of the gland in the surrounding connective tissue than inside the 

 basement membrane. The inside cells of this kind have more probably 

 been basal layer cells that have developed the oil-secreting power than 

 connective-tissue cells that have moved through the basement mem- 

 brane, carrying their load of secretion with them. 



These glands are present in most turtles, although not in all. They 

 are either lubricating glands or scent glands in all the cases in which they 

 occur, but are undoubtedly odorous in the animal in which we have stud- 

 ied them. Somewhat analogous glands are found in the integument of 

 other reptiles, sometimes on very different parts of the body, as the glands 

 on the jaw of .the alligator and the glands on the thigh of the lizard. 

 Some of these may not be glands for producing odor, but most of them 

 probably are. The secretion, it must be noted in this case as well as in 

 that of the skunk, is not discharged automatically, as in the lubricating 

 glands of the mammals (sebaceous glands) but is retained, and discharged 

 as needed. 



In some of the Amphibia an integumental gland is used to produce 

 an offensive fluid (said to be poisonous to some of its enemies). These 

 glands are somewhat like the surrounding lubricating or mucous glands 

 in the same animal's integument, and consist of single saccular glands 

 lined by a simple columnar epithelium. 



The so-called poison gland of Bufo will represent this class of tissue 

 as found in both the urodela and anura. This gland is vastly larger than 

 the mucous glands found in the same integument, although it is arranged 

 on much the same plan. A portion of its wall is represented in Figure 

 366. The cells, of the single layer of epithelium which lines it, develop 



