GLOSSARY 121 



chemical ferments in distinction to so-called organized or living ferments, 

 such as yeasts. 



Epithelium (plural, epitheliums; adjective, epithelial; from the Greek epi, 

 meaning "on" or "upon," and phele, meaning "nipple") ; a cellular tissue cover- 

 ing a free surface or lining a tube or cavity, and consisting of one or more 

 layers of cells with scarcely any intercellular substance, so that the cells form 

 a practically unbroken sheet or membrane. 



Ex-conjugant : either one of the two organisms which have recently been tem- 

 porarily united in conjugation (q.v.). 



Excretion : the process of ridding the body of products of destructive metabolism 

 (q.v.). Excretion, technically, must be distinguished from defecation, the 

 process of ridding the body of indigestible remains. 



Exosmosis : see Osmosis. 



Eye-spot : a small pigment body in certain unicellular algae, supposed to be sensi- 

 tive to light. 



Ferment: an agent capable of producing fermentation; sec also Enzyme. 



Flagellate : a one-celled organism, so named because one, two, or more flagella 

 are attached to the cell and serve as swimming organs. Flagellum is the Latin 

 for "whip." 



Flagellum (plural, flagella) : see Flagellate. 



Frustule : the siliceous shell of a diatom, composed of two valves, one overlapping 

 the other. 



Gamete: a sexual cell — either egg or sperm. 



Gametocyte (from the Greek, gamein, meaning "to marry" and kytos, meaning 

 "a hollow vessel") : technically the term is used to designate the cell which 

 gives rise to the gametes (q.v.). 



Gene: a hypothetical unit in a chromosome (q.v.) of the cell which has a specific 

 influence on a certain adult characteristic ; the unit of hereditary transmission. 



Genetics : the science which deals with the principles of heredity and variation and 

 the processes involved in the origin of species, races, and individuals. 



Germination: (1) beginning of growth or development of a spore; (2) resump- 

 tion of growth by the embryo of a plant. 



Germ-plasm : the substance composing the germ cells by which hereditary char- 

 acters are transmitted. 



Grape sugar : dextro-glucose ; called grape sugar because found in ripe grapes ; 

 it occurs in very many plants and in animal organisms; it is about half the 

 sweetness of cane sugar. Its formula is CeH^Oe. 



Hermaphrodite: an individual having both male and female reproductive organs. 



Histology : the branch of science which treats of the minute structure of normal 

 animals and vegetable tissues as discernible with the aid of the microscope; 

 microscopic anatomy. 



Holophytic (from two Greek words meaning all and plant) : wholly or distinc- 

 tively vegetable in nutrition; obtaining food after the manner of a green plant; 

 the process involves photosynthesis (q.v.). 



Holozoic (from two Greek words meaning all and animal) ; wholly or distinctively 

 like an animal as to nutrition; the process involves the digestion of solid 

 food substances. 



Hydrolysis : a chemical process of decomposition (see Decompose above) 

 involving the addition of the elements of water. Thus crystalline sugar when 

 dissolved has been hydrolyzed. 



Inclusion: a foreign body, usually of minute size, inclosed in a larger mass; 

 technically a foreign body inclosed in a cell. 



Infusion : water containing substances extracted from plant or animal matter. 

 Ordinary tea is an infusion. 



Inoculation : the introduction of bacteria or immune serum into living organisms ; 

 especially the introduction of disease germs or their products into a person in 

 health, by inserting them in his blood, in order to induce a mild form of the 

 disease which will secure immunity from future attacks, or will combat the 

 disease already present. 



Irritability : the response of an organism to stimuli ; it may be visible to the eye 

 in the form of movement, or it may be molecular and hence invisible. 



Kinetic elements : special bodies and fibers in a cell which have to do with move- 

 ment and with the transmission of stimuli to motile organs. 



