SUDORIPAROUS GLANDS. [ 746 ] 



SYCAMINA. 



into a knot near the closed end, which is 

 situated in the subcutaneous cellular tissue, 

 and forms the gland proper, and a straight, 

 undulate or spiral duct, which traverses the 

 skin perpendicularly, to terminate upon its 

 surface between the papillae. 



In the glands of the axilla, the portion 

 of the tube forming the gland proper is 

 branched ; and sometimes the branches ana- 



stomose. 



Portion of a tube with a muscular coat, from the scro- 

 tum, a, connective tissue ; 6, muscular layer ; c, epi- 

 thelial cells, filling the tube and containing yellow 

 granules. Magnified 350 diameters. 



The coiled portion or proper gland is sur- 

 rounded and permeated by an elegant plexus 

 of capillaries ; and some of them are sur- 

 rounded by a capsule of connective tissue 

 with spindle-shaped cells. 



The tube of the glands exhibits two forms 

 of structure. In one of these there is^an 

 outer coat of indistinctly fibrous connective 

 tissue with elongated nuclei, sharply defined 

 internally by probably a basement mem- 

 brane, this being lined with one, two, or 

 more layers of polygonal pavement-epithelial 

 cells, mostly containing fat-globules and 

 pigment-granules. 



In the other form, the fibrillation of the 

 connective coat is tolerably distinct, the 

 fibres longitudinal, sometimes also with an 

 inner, delicate transverse layer, and both 

 containing nuclear elastic fibres ; and within 

 this coat is a layer of longitudinal, unstriped 

 muscular fibres. 



The portion of the ducts traversing the 

 cuticle is spiral. 



It is by no means an easy matter to ob- 

 tain the sudoriparous glands in the entire 

 state. The skin of the palm of the hand or 

 the paw of a dog is best for the purpose j 

 and before making sections with a Valen- 

 tin's knife, the structure should be mace- 

 rated in a mixture of 1 part nitric acid and 

 2 of water, or in solution of carbonate of 

 potash. 



BIBL. Koliiker, Mik. An. ii. ; Todd and 

 Bowman, Phys. An. : Biesiadecki, Strieker's 

 Hist. ii. 238. 



SUGAR. This substance is liable to 

 fraudulent adulterations; and the coarser 

 kinds of brown sugar contain many im- 

 purities, such as Acari, fragments of the 

 cane, &c. Starch and flour are used to 

 whiten and give dryness to inferior moist 

 sugar ; and these may be detected by the 

 microscope (STARCH). 



The crystals of sugar of milk are repre- 

 sented in PL 10. fig. 12 ; and those of dia- 

 betic sugar in fig. 13. (Hassall, Food $c. 12 j 

 and the Bibl. of CHEMISTRY.) 



SURIREL'LA, Turpin. A genus of 

 Diatomaceae. 



Char. Frustules free, single, ovate, ellip- 

 tical, oblong, cuneate or broadly linear in 

 front view; valves with a longitudinal 

 median line or a clear space, the margins 

 winged, and with transverse or slightly 

 radiating canaliculi or tubular striae. 



It appears that in the valves the margins 

 of the depressions are fused together to 

 form tubular channels open at the ends. 



S. bifrons (Ehr. 1833 = & biseriata, Bre'b. 

 and Smith) (PI. 17. fig. 22). Frustules in 

 front view broadly linear, with rounded 

 angles ; valves elliptic-lanceolate, somewhat 

 obtuse ; alae and canaliculi distinct ; fresh- 

 water ; length 1-180 to 1-96". 



S. gemma (PI. 17. fig. 21). Frustules 

 ovate ; valves elliptic-ovate ; canaliculi nar- 

 row, inequidistant ; marine ; length 1-240". 



S. splendida. Frustules ovato-cuneate, 

 ends rounded ; valves ovato-lanceolate ; alae 

 and caualiculi distinct; freshwater; length 

 1-100". 



BIBL. Smith, J5r. Diatom, i. 30 ; Kiitz. 

 Bac. 59, and Sp. Alg. 34 ; Rabenht. Ala. i. 

 51. 



SWARMING. This term has been ap- 

 plied, from comparison with the swarming 

 of bees, to the remarkable oscillating 

 crowding movements of the spores of Con- 

 fervae &c. while free in the cavity of the 

 parent cell and preparing to break forth. 



The spores are hence often called "swarm- 

 ing-spores." See HYDRODICTYON. 



SYCAMI'NA, v. Tieg. A genus of 

 Volvocineae, composed of very minute 

 spherical, biciliated cells, associated in large 

 numbers to form a mulberry-like revolving 

 mass, the protoplasm being black or brown, 

 sometimes violet or reddish. S. nigrescens, 

 found at the bottom of ponds and aquaria, 

 forming a dark deposit, and producing the 



