INTEGUMENTAL GLANDS OF CROCODILIA 593 



Figure 29 shows the character of the cells in region 3 of figure 

 26, which covers more area of the segment than is shown in the 

 two preceding figures. Toward the periphery of the gland, to 

 the right in the figure, the cells are large and sharply defined, 

 with large, centrally located nuclei, and distinct cell walls, like 

 the cells in figure 28. As the cells are traced toward the lumen 

 of the gland, to the left in this figure, their clean-cut outlines 

 become irregular, the walls being shrunken and more or less 

 collapsed ; the nuclei are smaller and less numerous, and are gener- 

 ally located near or against the shriveled cell walls. To the ex- 

 treme left of the figure, which is practically the boundary of the 

 indefinite lumen of the gland, the cell-mass consists of what would 

 ordinarily be called adipose tissue. No, or few, nuclei are present, 

 and all that is seen is an irregular network of empty cell walls, 

 the oily contents having probably been dissolved out by the 

 preparation of the tissue for sectioning. In the middle of this 

 region, slightly indicated in the figure, the cells are often flat- 

 tened, as though by pressure from within outward. This flatten- 

 ing might possibly be caused by the pressure of the secretion of 

 the gland held within its central lumen. 



THE MANDIBULAR GLANDS 



The position of the mandibular glands is shown in figure 30, 

 which represents the ventral side of the head of a 20-cm. alligator; 

 this is the size of the animal on emerging from the egg. As seen 

 in figure 30, better in figure 31, the opening of the gland at this 

 stage is a longitudinally elongated slit, lying in a shallow groove 

 and bordered by irregularly elongated scales. In larger animals, 

 perhaps in those of this size, though the writer has never seen 

 it, the alligator may turn the gland partially inside out, as noted 

 above by Gadow, causing it to project above the surface of the 

 scales as a round or oval sort of rosette, with a circular or elong- 

 ated (fig. 36) central depression. The inside cells thus exposed 

 form an irregular, rough surface, so that the appearance is some- 

 what hke that of a partly expanded sea-anemone. Whether, in 

 their native habitat, the adult alligators evaginate the musk 

 glands whenever the musky odor is emitted, the writer is un- 



