56 Journal of Comparative Neurology. 



distinguished here as the ental and the ectal series. The glands 

 of the ectal series are distributed quite regularly throughout the 

 skin of the head, and occur together with those of the ental 

 series. In the latter case they are much smaller than the glands 

 of the ental series, being forced peripherad into the interstices 

 of the ental group which in places constitutes nearly the entire 

 integument beneath the Malpighian layer. 



Where the ental glands do not occur, those of the ectal 

 series may become very large in some instances, extending 

 through nearly the entire height of the corium and becoming 

 very closely crowded together. But regardless of position or 

 size, their structure is universally the same, and they are thus 

 easily distinguished from those of the ental series. The peri- 

 pheral cells of the ectal series are approximately cubical, becom- 

 ing lengthened or depressed according to the shape of the gland 

 and their position in it. The walls of these glands are made 

 up of such cells, supported externally by fibers of connective 

 tissue. There appear no differentiated muscular elements con- 

 nected with them. On the glands of the ental series the peri- 

 pheral structure is entirely different. As with the ectal series, 

 there is a tendency for the connective tissue to fold about them, 

 but within this tissue, lying compactly on the surface of the 

 gland, is a complete tunic of non-striated muscle cells. In a 

 section through the median plane of the gland this arrangement 

 is not noticable, but in sections just denuding the periphery of 

 the organ the form of these cells is plainly shown. They are 

 broad in their middle part and taper to a more or less acute 

 point at either end, being very much flattened throughout their 

 entire length. Their nuclei are large, elongated and rounded 

 at the ends. Each cell seems to be entirely separate from its 

 neighbor, there being frequently a considerable space between 

 them. This structure was first observed in tissues fixed in Flem- 

 ming's solution and stained by the Weigert method. (Fig. 7), 

 It has since been verified by sections of the same preparation 

 stained by the Delafield and Benda methods; in similar prepar- 

 ations double stained with picrocarmine ; also by the same 

 stains applied to tissues fixed in the chrom-acetic acid solution, 



