GLOSSARY. UKIC ACID WEIGHTS AND MEASfliKS. 613 



URIC ACID. An organic acid of the nrine the same as lithic acid, 

 but quite distinct from urea. It is an azotised chemical substance 

 Seep. 311. 



VAGUS NERVE or PAR VAGUM. The eighth pair of cranial nerves. 



VALVUL^E CONNIVENTES. Transverse folds of the mucous membrane 

 of the small intestines, by which the extent of its surface is very 

 much increased. They extend in man from the duodenum to the 

 middle of the ilium. They are much less conspicuous in other 

 animals. 



VASCULAR GLANDS. Ductless glands which abstract material from the 

 blood as it circulates through them, and then restore the elaborated 

 matter to the blood within their own boundary, or to the lymph- 

 atic vessels that issue from them. 



VENA PORT.E or VENA PORTARUM. The vein which enters the liver 

 and is distributed like an artery. It is a trunk formed from all the 

 veins that correspond to the cceliac axis the superior mesenteric 

 and inferior mesenteric arteries, even the hepatic artery, finally 

 communicating its blood to the minute branches of the vena por- 

 tarum within the liver. 



VILLI OF INTESTINES. Minute vascular processes of mucous mem- 

 brane, each containing a delicate network of blood-vessels and one 

 or more lacteals, by means of which the chyle is conveyed from 

 the small intestines into the lacteal system. 



VOCAL CORDS. See Glottis. 



WEIGHTS AND MEASURES. The standard of weight used in this 

 country is the avoirdupois pound, which contains 7000 grains. In 

 this pound there are sixteen ounces, so that each ounce contains 

 437.5 grains. In an imperial gallon there are 70,000 grains of 

 distilled water ; that is to say, 10 Ib. avoirdupois. A cubic inch 

 of distilled water contains 252.456 grains at 62 Fahr. with the 

 barometer at 30 in. ; in vacuo, at the same temperature, the weight 

 is 252.722 grains. In an imperial gallon there are 277.276 cubic 

 inches. 



It is hardly possible at present to dispense with a knowledge of 

 the modern French system of weights and measures. 



The measures of length stand first in the French system, and of 

 these measures the metre may be called the basis. The metre ex- 

 ceeds the English yard by nearly three inches and a half, being 

 equal to 39.37079 English inches. It is a little more than the 

 fifth part of an inch longer than a pendulum which beats seconds 

 in vacuo at the level of the sea in the latitude of Greenwich. 

 Forty millions of metres make a great meridional circle of the 

 globe. The metre is divided into tenths, hundredths, and thou- 

 sandth parts, termed respectively decimetres, centimetres, and 



