stolzite (stolzit)

[Named after Dr. Stolz of Teplitz in Bohemia.] Native lead tungstate, a mineral occurring in tetragonal crystals of a green, brown, or red color, and resinous or sub adamantine luster. Sometimes called scheeli tine. stoma (stō'mä), n.; pl. stomata (-ma-tä). [NL., mis of leaves, etc., which opens directly into air-cavities or intercellular spaces Longitudinal Section that pervade the interior, of a Stoma taken from and through which free inperfoliata. (Magnigre and egre of air take place; a breathing-pore. The apparatus of the stoma consists usually of a pair of cells (there are several in the Equisetaceæ, Hepaticese, etc.), called guard -cells or guardian -cells, between the opposed concave sides of which lies the slit or opening, which extends through the whole height of the epidermis and permits free communication between the intercellular spaces and the external air. According to Van Tieghem, the stomata are always open in sunlight and closed in darkne . These cells are strongly thickened on the upper and under walls of their opposed faces, while elsewhere their walls are rela 2 3 tively thin. The opening and variegatum. 3. Limnocharis Plumier i, a, closing of a sto- Stomata. (Magnified.) ma depend upon 1. Strobil ant hes Sabin i an us. 2. Codiæum the difference in thickne of the parts of the walls. When the turgescence of the guard-cells increases, they curve more strongly, and consequently the cleft widens; but with decreased turgescence the cleft becomes narrower. See also cut under Iris. stomach vary greatly in different individuals and in different states of distention. It begins where the gullet ends, at the esophageal or car IMG:content-2175.jpg:[graphic] diac orifice, and ends at the pyloric orifice, where the duodenum f begins. From the car ach bulges to the left in a great cul-de-sac, the fundus cardiac us, or cardiac end, in contact with the spleen, and from this greatest caliber the organ le ens in diameter with a sweep to the right. The le er curvature or short border of the stomach, between the cardiac and pyloric orifices, is uppermost, and is connected with the liver by the le er or gastrohepatic omen tum. The greater curvature or long border of the stomach is opposite the other, between orifice the stom IMG:content-2176.jpg:[ocr errors] Human Stomach and Beginning of Intestine, laid open to show ruge. a, esophagus or gullet; b, cardiac (left) dilatation of stomach; c, le er curvature of stomach, opposite which is the (unlettered) greater curvature; d, pylorus, at right extremity of stomach; e, biliary or hepatic duct; f, gall-bladder, whose duct, the cystic duct, forms with the hepatic duct the duct us communis choledochus, or common bileduct; &. pancreatic duct, opening into the last; i, duodenum, or beginning of the small intestine. the same two points, and gives attachment to the great or gastrocolic omentum. These two curvatures separate the anterior and posterior surfaces. The stomach is held in place by folds of peritoneum, the gastrocolic, gastrohepatic, gastrosplenic, and gastrophrenic omenta, the last of which gives it most fixity. The arteries of the stomach are the gastric (a branch from the celiac axis), the pyloric and right gastro-epiploic branches of the hepatic, the left gastro-epiploic, and short branches from the splenic artery. The veins end in the splenic, superior mesenteric, and portal veins. The numerous lymphatics consist of a deep set and a superficial set. The nerves are the terminal branches pneumogastrics and many branches from the sym IMG:content-2177.png:[blocks in formation]