200 SPECIAL HISTOLOGY. 



and at tolerably equal distances apart ; in other places they are met 

 with, usually in a regular manner, singly or in pairs, in each mesh of 

 the corium, although, according to Krause, spaces of J-J a line exist, 

 where they are totally absent, or occur in groups of three or four 

 close together. In the axilla, the glands form a connective layer under 

 the corium. 



According to Krause, there occur on a square inch of the skin be- 

 tween 400 and 600 glands on the back of the trunk, the cheeks, and the two 

 superior segments of the lower extremities ; 924-1090 on the anterior 

 part of the trunk, on the neck, brow, the forearm, back of the hand 

 and foot ; 2685 on the sole of the foot ; and 2736 on the palm of 

 the hand. The total number of the sudoriparous glands, without reck- 

 oning those of the axilla, is estimated (somewhat too highly) by Krause 

 at 2,381,248, and their collective volume (with those of the axilla) at 

 39,653 cubic inches. 



The vessels of the sudoriparous glands are particularly well seen in 

 those of the axilla (Fig. 78) ; in others, the vessels may also be seen 

 here and there (best in the penis, where, for example, glands of 0-36 of 

 a line are supplied by the most delicate ramifications of an artery of 

 0-06 of a line, in their interior); and in successful injections of the 

 skin, the glands appear as reddish corpuscles. Nerves have not hitherto 

 been found in them. 



67. Intimate Structure of the Glandular Coil. The sudoriparous 

 glands, in general, consist of a single much convoluted canal (in one 

 case, according to Krause, } of a line long), twined into a coil, 

 which retains pretty nearly the same diameter throughout its length, 

 and terminates, either upon the surface of the coil, or in its interior, in 

 a slightly enlarged blind extremity. In the large glands of the axilla 

 alone, the canal is usually divided, dichotomously, into branches, which 

 subdivide, and sometimes, though rarely, anastomose ; and after giving 

 off small caecal processes, each separate branch finally terminates in a 

 blind extremity. The glandular canals have either thin or thick walls 

 (Fig. 79). The former (Fig. 79 A) possess an external fibrous invest- 

 ment, consisting of indistinctly fibrous connective tissue, with scattered 

 elongated nuclei ; internally this is sharply limited, perhaps by a mem- 

 brana propria, and is covered by a single, double, or multiple layer of 

 polygonal cells of 0-005-0-007 of a line, which in their chemical rela- 

 tions, and otherwise, correspond perfectly with the deep cells of pave- 

 ment-epithelium, except that they almost invariably contain a few fatty 

 granules, and still more frequently a small quantity of yellowish or 

 brownish pigment-granules. 



The thick-coated sudoriparous glandular canals (Fig. 79 B] possess, 

 besides the two layers just described, a middle layer of smooth muscles 



