SALICINE. 



[ 559 ] 



SARCINA. 



grains resemble those of the East Indian 

 Arrow-root (PI. 36. fig. 18). See Starch. 



SALICINE.— The alkaloid of the T\illow 

 and ])oplar. 



The so-called circular crystals of this sub- 

 stance (PI. 31. fig. 9) form a beautiful polar- 

 izing object. The largest crystals are ob- 

 tained by fusion. 



SALIVARY GLANDS.— These organs, 

 consisting of the parotid, the submaxillary, 

 and the sublingual glands, agree in structure 

 with the racemose mucous glands (Mouth), 

 of which they may be regarded as aggrega- 

 tions. 



Their ducts consist of areolar tissue, with 

 numerous very dense networks of elastic 

 tissue. Wharton's duct contains unstriped 

 muscular fibres. 



The salivary corpuscles are noticed under 

 Mouth (p. 439). 



SALPINA, Ehr. — A genus of Rotatoria, 

 of the family Euchlanidota. 



Char. Eye single, cervical ; foot forked ; 

 carapace closed on the ventral surface, and 

 furnished with spines or horns at the ends. 

 Aquatic. 



The carapace resembles a three-sided box 

 with convex sides, flat and closed beneath, 

 and often scabrous. 



S. redunca (PI. 35. fig. 24). Carapace 

 with two curved horns in front upon the 

 ventral surface, smooth, posterior end with 

 three horns ; dorsum cleft, gaping. Length 

 of carapace 1-216 to 1-144". 



Five other species. 



BiBL. Ehrenberg, Infus. p. 469. 



SALTS. See Crystals. 



SALVIA, L. — An extensive genus of 

 Flowering plants of the Nat. Ord. Labiatae, 

 including common sage, and many species 

 cultivated for the beauty of their flowers. 

 They are interesting to the microscopist both 

 on account of the Glandular hairs, 

 containing the essential oils, and the spiral- 

 fibrous structures found in the Hairs of 

 the pericarp (PI. 21. fig. 23). 



SALVINIA, Mich.— A genus of Marsi- 

 leaceae, growing floating on the surface of 

 stagnant water (not British). They are di- 

 stinguished fromMARSiLE a and Pi lularia 

 also by bearing two distinct kinds of spore- 

 fruits, one kind producing only ovule-spores, 

 the other only pollen-spores, which exhibit 

 analogous phsenomena in their germination 

 to those described under Pi lularia. See 

 that head and Marsileace^. 



BiBL. That of Marsileace^ and Pilu- 

 laria. 



SAND, Brain-. — Brain-sand, or the acer- 

 vulus cerebri, is found in the pineal gland 

 and the choroid plexus, sometimes also in 

 the pia mater, the arachnoid membrane, and 

 the walls of the ventricles. 



It consists of single, or aggregated and 

 nodular, rounded, dark bodies, 1-2500 to 

 1-200" in diameter; sometimes also forming 

 club-shaped, cylindrical, or reticular masses. 

 Chemically it is principally composed of 

 carbonate and phosphate of lime, and like 

 other concretions, leaves an organic cast of 

 the original form, after the salts have been 

 removed by a dilute acid. 



Fig. 628. 



Brain-sand from the pineal gland, in bundles of areolar 

 tissue. 



Magnified 350 diameters. 



BiBL. Kolliker, Mikrosc. Anat. ii. 



SAND, Sea. — This often contains inter- 

 esting microscopic objects ; as Foraminifera, 

 spicules of sponges, minute shells of the 

 MoUusca, or their fragments, portions of the 

 skeleton of the Echinodermata, &c. 



The various bodies may be separated from 

 the washed and dried sand with a mounted 

 bristle (Intr. p. xxii.). 



The sand or powder which may be sepa- 

 rated by pressing or shaking newly imported 

 sponges, and which is sometimes called 

 sponge-sand, is very rich in the above organic 

 bodies, especially the Foraminifera. 



SAP. — A name vaguely applied to the 

 watery juices contained in living plants. 

 Sap flowing from wounds may contain va- 

 rious organized substances, such as starch- 

 granules, chlorophyll- or protoplasmic glo- 

 bules, also raphides ; but it cannot be said 

 to have any proper microscopic characters. 



SAPROLEGNIA, Nees. See Achlya. 



SARCINA, Goodsir. — A curious organ- 

 ism, placed provisionally among the Pal- 



