GLOSSARY 301 



Diastases — also known as ferments or enzymes : they are sub- 

 stances which can produce fermentations in the absence of 

 living cells : their chemical nature is unknown and they are 

 defined simply by their activities : they occur in the form of 

 organic substances of indefinite composition vi-hich are soluble 

 in water. In the embryo of grain (barley, &c.) there exists a 

 diastase vi'hich transforms the starch of the grain into sugar in 

 the presence of warmth and moisture, the process of " malting." 

 ( Vide Fermentation.) 



Electrolytes — bodies which in solution break up into "ions" 

 carrying electrical charges which are equal and opposite. For 

 example, common salt in solution in water breaks up into a 

 sodium ion carrying a charge of negative electricity, the cation 

 and a chlorine ion carrying a charge of positive electricity the 

 anion. The presence of electrolytes in water renders it a good 

 conductor of electricity, hence the name. 



Enzymes — vide Diastases. 



Epizootic— infectious disease occurring widespread among animals 

 — contrasted with " epidemic " in which the disease affects 

 man. 



Fats — compounds of carbon, oxygen, and hydrogen in the form of 

 "esters" of glycerine, i.e.^ compounds of glycerine with a fatty 

 acid. Palmitin, stearin, and olein are fats in which glycerine 

 is combined with palmitic, stearic, and oleic acids. The 

 natural fats are mixtures in varying proportions of palmitin, 

 stearin, and olein. The "saponification" of fats is their 

 decomposition into the two elements glycerine and fatty acid, 

 and the combination of the latter with sodium or potassium 

 (" salting out " in the language of soap manufacture). Soap is 

 thus a salt of sodium or potassium with a fatty acid, e.g., 

 stearate of sodium. By saponification loo grams of fat can 

 furnish 90 grams of fatty acid. 



Fermentation — a chemical transformation produced by the action 

 of living cells, e.g., the cells of the yeast of beer, or by the 

 action of the secretions of these cells (diastases), e.g., zymase 

 extracted from yeast cells. A typical fermentation is that of 

 sugar by yeast in which the sugar is broken up into carbonic 

 acid, water, and alcohol. 



Fibrin — a protein (more exactly, a globulin) which forms the clot in 

 coagulated blood. It does not exist in circulating blood in the 

 living animal, but is derived from a different substance which 

 exists in this and is termed fibrinogen. " Defibrinated" blood 

 is blood ■ from which the fibrin is removed as it forms by 

 whipping with a bunch of twigs immediately after the blood is 

 drawn. Such blood is no longer capable of coagulation. 



Flora — the aggregate of plants growing without cultivation in a 

 given district or indigenous to a particular geological formation : 

 hence applied to the aggregate of bacterial species inhabiting 

 the intestine, the mouth, &c. 



