INTEGUMENTAL GLANDS OF CROCODILIA 583 



center of the gland than nearer the periphery, thus foreshadowing 

 the condition seen in the mature gland. The cells are small, 

 compared to the size of their nuclei, and of indistinct outlines. 

 In pushing down into the underlying muscular tissue the gland 

 has carried with it a thin surrounding layer of the corium as a 

 sort of connective-tissue sheath or capsule, cp. 



The next embryo studied (fig. 6) had a total length of about 

 13 cm. The gland here (fig. 7) is distinctly flask-shaped, the 

 neck of the flask forming the wide duct, d, which is plugged with 

 a fairly compact mass of cells. The more bulging side of the 

 fundus is toward the median plane of the animal, to the right 

 in figure 7. The fundus of the gland, g, projects well down 

 into the underlying muscular tissue, m, and is surrounded by a 

 thick, though loose, connective-tissue capsule, cp. 



The epidermis, ep, contains numerous pigment granules that 

 mask somewhat the cell details. It extends down into the duct 

 to about the region where the enlargement to form the gland 

 proper begins ; here it gradually becomes thinner and finally merges 

 into the cell mass of the gland. As seen in figures 7 and 8 there 

 are irregular spaces among the cells of both gland proper and 

 duct. The cell details at this stage are very difficult to determine 

 with accuracy. 



Figure 8 represents a section through the fundus of the gland, 

 six sections anterior to the one shown in figure 7. The gland, 

 which is now beginning to approach the adult structure, consists 

 of a mass of irregular, often elongated, cells, with oval nuclei. 

 Around the periphery is a more or less distinct row of nuclei, 

 belonging to a sort of layer of basilar cells, to be noted in a 

 later stage. In the irregular central cavity or lumen may 

 usually be seen a few scattered cells ; whether these are 

 artificially torn off or are regularly desquamated from the under- 

 lying cells it is not easy to determine. The lumen, lu, if it 

 may be so called, being so irregular in outline, it is not possible 

 to say just how many layers of cells make up the wall of 

 the gland. In some places the lumen extends to within one or 

 two cells of the peripher}^ ; in other regions there are six or more 

 irregular layers of cells. Further discussion of these cells will be 



