GLOSSARY. CALCIUM CELL. 589 



CALCIUM. One of the earth metals, the oxide of which is common 

 lime. It is a light metal, and decomposes water readily with the 

 evolution of hydrogen. It may be obtained from the iodide of 

 calcium by means of sodium. It exists abundantly in organic 

 nature. See p. 304. 



CALEFACIENT or CALORIFIC FOOD. The same as non-azotised food. 



CALYCES. The calyces of the kidney are the extremities of the subdi- 

 visions of the pelvis of the kidney which receive the urine from the 

 apices of the cones of Malpighi ; less numerous than the apices of 

 the cones, because more than one apex is often inserted into one 

 calyx. 



CAPILLARIES. The capillaries form a network of blood-vessels at a 

 medium diameter, about 1 -3000th of an inch, interposed between 

 the arterial system and the venous system. 



CAPSULES OF MALPIGHI. Small flask-shaped dilatations at or near 

 the commencement of the minute tvbuli uriniferi in the kidney. 

 Within or attached to these capsules lies a Malpighian corpuscle or 

 tuft, the ultimate structure of the kidney. 



CARBON. A simple non-metallic combustible body, existing in mineral 

 nature chiefly in combination with oxygen under the form of car- 

 bonic acid ; its common type is the charcoal of wood. It is an 

 essential constituent of all organic substances. See p. 297. 



CARBONIC ACID. A gaseous acid, consisting of carbon and oxygen. 

 It exists in small proportion in the atmosphere, w r hence plants 

 draw it as a principal part of their food. It exists abundantly in 

 mineral nature as combined with lime and magnesia. Several 

 carbonates are found in animal nature, as the carbonate of potash, 

 the carbonate of soda, the carbonate of lime. 



CARDIA. The upper or oasophageal orifice of the stomach. 



CAROTIDS. The principal arteries supplying blood to the several parts 

 of the head and brain. 



CARTILAGE. The same as gristle. 



CASEINE. A proximate principle of organic nature azotised, obtained 

 from poor cheese. See p. 307. 



CASTRATION. See Genital organs. 



CATALYSIS. Catalytic action in chemistry is when a body, without 

 being itself changed, by its mere presence originates chemical ac- 

 tion between other bodies ; for example, spongy platinum being 

 present in a mixture of oxygen and hydrogen, these last unite to 

 form water. 



CAUDA EQUINA. The spinal marrow terminates in a slender filament, 

 which, being surrounded by the roots of many nerves, is termed 

 the horse-tail, or cauda equiua. 



CELL. A vesicle. Cells, such as epidermis cells, lymph cells, consist 

 of a cell- wall and nucleus, or cytoblast, with a contained fluid ; 

 cells in the most developed state, as the blood-corpuscles of mam- 



