THE USE OF A DIVERTICULUM. 235 



DIABE'TES. A disease characterized by great augmentation and 

 often manifest alteration in the secretion of urine, with ex- 

 cessive thirst and progressive emaciation. The quantity of 

 urine discharged in 24 hours is sometimes 30 pints and up- 

 ward, each pint containing 2y ounces saccharine matter. 



DI'APHRAGM. 1. A dividing membrane or thin partition, com- 

 monly with an opening through it. 2. The muscle separa- 

 ting the chest or thorax from the abdomen or lower belly ; 

 the midriff. Webster. 



DIATH'ESIS. Disposition, constitution, affection of the body ; 

 predisposition to certain diseases rather than to others. The 

 principal diatheses are the cancerous, scrofulous, scorbutic 

 (pertaining to scurvy), rheumatic, gouty, and calculous. 



DIVERTTC'TILUM. A blind tube branching out from the course 

 of a larger one. An organ which is capable of receiving an 

 unusual quantity of blood, when the circulation is obstructed 

 or modified elsewhere, is said to act as a diverticulum. 



In the marsupials only four teeth (one in each jaw on each 

 side) are deciduous. The permanent set are developed from 

 diverticula of the sacs which originated the first set. Gilt. 



DUGONG' . A herbivorous, cetaceous animal with a tapering body 

 ending in a crescent-shaped fin. The mbled mermaid seems 

 to have been founded on the dugong. (Ziloert. Brande. 

 It is generally from 8 to 12 feet long, though it is said to 

 sometimes attain the length of 25 feet. The upper lip is 

 thick and fleshy and forms a Kind of snout; the upper jaw 

 bends downward almost to a right angle ; eyes small, with a 

 nictitating membrane ; tne skin is thick and smooth. Its 

 flesh is said to resemble beet, and is prized as food. The oil 

 is recommended as a substitute for cod -liver oil. J.'s Cyc. 



DURA MATER. (Hard.) The outermost of three membranes 

 enveloping the brain and spinal cord. Within the skull 

 it so completely joins the bones that it may be regarded 

 as their endosteum. Within the spinal canal it becomes 

 a fibrous tube, separated from the vertebrae (which have 

 no endosteum; by a loose, areolar, fatty tissue and a plexu 

 of veins. It sends out sheaths for the nerves as they go 

 through their foramina. It is usually studded, except in 

 infancy, by minute whitish masses (Paccionian bodies) whose 

 use is not known. Its inner surface is covered with pave- 



