GLOSSARY 499 



Family. In classification, a main subdivision of an order. See 

 Genus. 



Fats. One of the chief groups of foodstuffs. Compound (esters) of glyc- 

 erol with a fatty acid; e.g., mutton tallow is chiefly the fat stearin 

 (C 5 7Hiio0 6 ) = glycerin plus stearic acid. More oxidizable than carbo- 

 hydrates. See Lipids. 



Fermentation. The transformation of carbohydrates by the activity of 

 ferments, or enzymes, derived from living organisms. See Putrefaction. 



Fertilization. The union of male and female gametes, especially their 

 nuclei, by which the chromatin complex of each is arranged to form the 

 composite nucleus (synkaryon) of the zygote. 



Fetus. An embryo of a Vertebrate, in egg or uterus. 



Flagellum. A whip-like prolongation of the cytoplasm, the movements 

 of which usually effect the locomotion of the cell; e.g., Euglena. 



Fluctuations. Relatively slight variations, usually forming a finely 

 graded series, always found in organisms; may be either modifications or 

 recombinations, but usually the former. 



Fungi. Colorless plants; e.g., Racteria, Yeast, Mushrooms. 



Gall Rl adder. Receptacle near the liver for the temporary storage of 



bile. 

 Gamete. A cell which unites with another at fertilization to form a zygote. 



Egg or sperm. 

 Gametic Nuclei. Nuclei of gametes that unite to form the synkaryon, 



or nucleus of the zygote. 

 Ganglion. A group of nerve cells, chiefly the cell bodies, with supporting 



cells. 

 Gastric Vacuole. A droplet of fluid enclosing ingested food, in which 



digestion occurs; e.g., in Amoeba and Paramecium. Food vacuole. 

 Gastroliths. Calcareous bodies found at certain times in the lateral 



walls of the stomach of the Crayfish. Probably represent the storage of 



material for the exoskeleton. 

 Gastrula. A stage in animal development in which the embryo consists 



of a two-layered sac, ectoderm and endoderm, enclosing the enteric 



cavity which opens to the exterior by the blastopore. 

 Gemmule. An asexual reproductive body liberated by certain Sponges. 

 Gene. Independently inheritable factor or element in the chromosomes 



which influences the development of one or more characters in the 



organism. Presumably a protein molecule. 

 Genetics. The science of heredity. 

 Genotype. The fundamental hereditary constitution of an organism or 



group of organisms. The gene complex of an organism. See Phenotype. 

 Genus. In classification, a main subdivision of a family. See Species. 



