Digenesis

Same as PARTHENOGENESIS, q. v. Dig'enite, n. ( Min.) An orthorhombic mineral. Sp. gr. 5-5 to 5.8. Lustre metallic. Color and streak blackish, lead-gray. Comp. sulphur 20-2, copper 79-8 = 100. In the United States, compact varieties occur in the red-sandstone formation at Limebury and Cheshire, Conn.; also at Schuyler's Mines, N. J. Digest, ( de -jest',) v. a. [Lat. digero , digest us - dis , and gero, to bear about with one, to wear. See GESTATION.] To separate or di olve, and concoct in the stomach, as food; to convert into chyme. To distribute into cla es; to arrange or dispose methodically; to draw out methodically in the mind; to dispose and nourish in the mind, so as to improve the understanding and heart. "Read, mark, learn, and inwardly digest."- Book of Com . Prayer. -To receive and enjoy; to brook. "With my two daughters' dowers, digest the third." - Shaks. -To receive without open resentment, repugnance, or rejection; as, to digest good counsel. - To soften, abate, or reduce, as anger or other pa ions. To mature; to bring to ripene or perfection. "Learning, digested well." Thomson. (Chem.) To soften and prepare by caloric, or heated moisture. Hydrochloric acid Chloride of sodium Cane-sugar Albumen... Caramel IMG:content-0607.png:[blocks in formation] arrangement; a body of laws arranged under proper titles; any collection, compilation, abridgment, or summary of laws, or of the principles of any other science, disposed under proper heads or titles. ( Civil Law .) A term often applied to the Pandects of the civil or Roman law. It was compiled from the works of previous Roman jurists by Tribonian and others, at the command of the emperor Just in i an, and was published in A. D. 533. ducing to cla ification and method. "The digestion of the counsels in Sweden is made in the senate." Temple. (Surg.) A term formerly applied to the treatment by which wounds or ulcers were brought into that state in which they found healthy pus; the remedies or applications promoting this object were termed digestives. (Chem.) The heating of a substance in a liquid, in order to extract some principle contained in it. It is distinguished from maceration by being performed at a high temperature. (Physiol.) That proce by which the food of animals is converted into chyme in the stomach, and prepared for being ultimately taken into the blood. The function or proce of D. is one of the principal of those that are directly concerned in the maintenance of life; and hence its proper performance is of the utmost importance to the individual; while depending, as it does, upon the healthy condition of a great number of organs, it is not to be wondered at that it is liable to disorders, and is productive of an endle variety of diseases under the general term indigestion . The principal proce es connected with digestion are usually represented as 1. Mastication ; 2. Insalivation ; 3. Deglutition ; 4. Chymification , or the action of the stomach; 5. Chylifi cation, or the action of the intestines; 6. Defecation; and 7. the absorption of the chyle. The operation of mastication is a very important auxiliary to D. , since the more food is broken down and mixed with the saliva, the more readily and completely will it be acted upon by the stomach. Imperfect mastication is a frequent cause of indigestion. During this proce the salivary glands yield up their contents, by means of which the dry food is moistened and rendered more fit for deglutition. The third proce is the act by which the food is transferred from the mouth to the stomach. (See DEGLUTITION.) The alimentary matter being propelled by the contractions of the œsophagus into the cardiac extremity of the stomach, is there acted upon and di olved by the gastric juice, which is secreted by glands lying in its inner or mucous coat. This proce is a isted by the muscular contractions of the stomach, by means of which the ma is kept in motion until it is formed into chyme. When it has been sufficiently operated upon, it pa es through the pyloric opening into the duodenum. The pylorus po e es a peculiar sensibility, that prevents any matter from pa ing through it but such as has been properly converted into chyme. Recent investigations have shown that the changes which the food undergoes in the stomach are e entially chemical. IMG:content-0608.png:[blocks in formation] Fig . 821.- ALIMENTARY CANAL. a, œsophagus: b, stomach; c. cardiac orifice; d, pylorus; e, small intestine; 1, biliary duct; g, pancreatic duct; h ascending colon; i transverse colon; descending colon; k , rectum. (See GASTRIC JUICE.) The proce of gastric D. is very slow. It is more than an hour before the food suffers any apparent change; and the ordinary time required for the D. of animal food is from three to four hours. The chyme having pa ed through the pylorus into the duo denum, mixes with the biliary, pancreatic, and intestinal secretions. These juices, by their action upon the chyme, separate it into two portions, -one a milky fluid called chyle, the other the excrementitious portion. The bile seems to be of use principally in promoting the digestion of fatty matters, while the pancreatic juice serves mainly to convert starchy matters into sugar. Of the use of the intestinal juice little is known. The chyle attaches itself to those irregular circular folds of the mucous membrane of the small intestines, called the valvulæ conniventes, where it is absorbed by the lacteals. The large intestines also po e lacteals; so that, if any portion of the chyle should not have been absorbed in the small intestines, it is taken up in the large one. The fæces pa gradually from the small to the great intestines, until they reach the rectum, in which they are retained for some time, and then discharged. The absorption of the chyle forms the last act in the proce of D. It is, as we have already seen, taken up by the lacteals, and is by them conveyed to the mesenteric glands, where it is supposed to undergo some change. From thence it makes its way to the right side of the aorta, in the lumbar region, where it is finally discharged into an elongated pouch, called the receptaculum chyli. From this pouch the thoracic duct conveys the chyle upwards to the left side of the neck, where it is poured into the left subclavian vein at its junction with the internal jugular, and, being thus mixed with venous blood, it is carried to the lungs and there converted into new and perfect arterial blood. Digestive, a. [Fr. digestif .] Having the power to cause digestion in the stomach; as, a digestive tonic. -Capable of softening and preparing by heat. -Methodizing; cla ifying; reducing to form and order. "To busine , ripen'd by digestive thought, This future rule is into method brought." - Dryden. -n. (Med.) That which increases or aids digestion. (Surg.) See DIGESTION. Dig'gable, a. That may be digged. Dig'ger, n. One who digs; as, a gold - digger . (Agric.) An instrument resembling a spade, used for digging. Digger Indians, a name applied to several tribes of miserable and degraded Indians in Oregon and California, who subsist on roots which they dig out of the earth, and on insects, lizards, . They are believed to be the lowest grade of humanity upon earth. Digges' Islands, ( dīgz , ) a group of 3 small islands in the Arctic Ocean, on the W. side of Hudson's Strait. Lat. 62° 37′ N., Lon. 70° 18' W.