MESENTERICA. 159 



skin. To cure mange, destroy the insect. (See Skin 

 Diseases.) 



Materia Medica. — This is a name applied to every 

 substance used in the treatment and cure of disease. 



Megrims. — A disease of the brain occurring at periods, 

 especially in hot weather, and when exposed to a powerful 

 sun. This differs from epilepsy only in the absence of 

 spasms. (See Epilepsy.) 



Causes. Tumors in the choroid plexus, and enlargement 

 of the pineal gland. 



Treatment Merely palliative, by using a dutch collar, 

 so as not to interfere with the circulation of the blood from 

 the head. 



Observe. In summer the horses subject to brain disease, 

 or fits of any kind, should not be used for family purposes. 

 In winter they will make useful animals. 



Melanosis. — A variety of cancer peculiar to gray 

 horses, which turns white with age, and is caused by the 

 transfer of the coloring pigment from the skin to the blood. 

 (See Cancer.) 



Melanoid. — (See Cancer and Tumors.) 



Mesentery. — A membrane formed of two folds of the 

 peritoneum, between each of which there are numerous 

 glands, lacteals, lymphatics, arteries, veins and nerves. It 

 is called the mesentery, because it adheres to three lumbar 

 vertebrae, and has the small intestines hanging to it. One 

 portion of it is called the mesocolon — supporter of the colon 

 — and another the mesorectum, which encloses the rectum. 



Mesenterica. — Wastino^ of the mesenterv is a disease 

 which is not very common to horses, although some clearly 

 marked cases are sometimes seen, characterized by wasting 



