352 Life and Health 



Vas'cu-lar (Lat. vasculum, a little vessel). Pertaining to or possessing 

 blood or lymph vessels. 



Va / sO-mo / tor (Lat. vas, a vessel, and movere, motum, to move). Causing 

 motion to the vessels. Vasomotor nerves cause contraction and relaxa- 

 tion of the blood vessels. 



Ve'nae ca'vse, pi. of vena cava. Literally, " hollow veins " ; a name given 

 to the two great veins which meet at the right auricle of the heart. 



Ven'ti-la'tion (Lat. ventilare, to fan). The process of replacing the foul or 

 vitiated air in any room or confined space with air that is pure. 



Ver'mi-form (Lat. vcrmis, a worm, and forma, form). Worm-shaped. 



Ves'ti-bule (Lat. vestibulum, a porch). A portion of the internal ear, com- 

 municating with the semicircular canals and the cochlea. 



Villi (Lat. villus, shaggy hair). Minute thread-like projections upon the 

 internal surface of the small intestine. 



Vi'rus (Lat., poison). The poison of an infectious disease, especially one 

 found in the secretions or tissues of an individual or animal suffering 

 from an infectious disease. 



Vi'tal knot. Common name for that part of the medulla oblongata the 

 destruction of which causes instant death ; the respiratory center. 



Vit're-ous (Lat. vitrum, glass). Having the appearance of glass ; applied 

 to the humor occupying the largest part of the cavity of the eyeball. 



Viv / i-sec / tion (Lat. vivus, alive, and secare, to cut). Dissection of a living 

 animal ; experimentation upon an animal while still alive. 



Vo'cal cords. Two elastic bands or transverse folds of the larynx. 



X-rays, or Roentgen-rays. The peculiar ether rays or waves discovered 

 by Roentgen in 1895. These rays penetrate substances like wood, the 

 bodily tissues, and many other substances which are opaque to the light 

 of the sun ; extensively used in the diagnosis of surgical cases. 



Zy-go'ma (Gr. $vy6i>, a yoke). The arch formed by the malar bone and 

 the zygomatic process of the temporal bone. 



