GLOSSARY 



A glossary is a partial dictionary of the words used in a book. In this glossary you 

 will find short explanations or definitions of a great many of the words that are used 

 in biology. These are called "biological terms," although some of them are used in 

 other sciences as well as in biology. Some words have one meaning in biology and 

 one or more meanings in other sciences or in ordinary conversation or writing. In 

 this glossary the biological meaning of such words is given, so you must take care in 

 using these definitions. 



Some of these terms are often pronounced incorrectly. To help you with these a 

 phonetic pronunciation is given in parentheses. 



abdomen (ab-doh'men) : the posterior (hind) re- 

 gion of an arthropod's body; in the higher 

 vertebrates that part of the body which con- 

 tains the stomach and lower digestive organs. 



abscess (ab'sess) : a gathering of pus accompa- 

 nied by inflammation in a definite spot in the 

 body, usually caused by bacteria. 



absorption (ab-sorp'shun) : the movement of wa- 

 ter, digested food, and other soluble sub- 

 stances into the blood or cells of animals; in 

 plants, diffusion of soil water into the root. 



acne (ack'knee) : a skin condition which shows as 

 an eruption, especially on the face. 



acquired characters: characteristics or traits of or- 

 ganisms developed during their lifetimes in 

 response to environment. 



acromegaly (ac'row-meg'al-ly) : a condition in 

 man and other mammals caused by excessive 

 secretion of the pituitary gland, showing it- 

 self in enlargement of certain bones, such as 

 those of the feet, hands, and parts of the face. 



adaptation (a-dap-tay'shun) : any change in the 

 structure or activities of organisms which fits 

 them for their environment. 



adrenal (ad-ree'nal) glands: ductless glands, one 

 next to the upper end of each kidney, secret- 

 ing adrenin and cortin and probably other 

 hormones. 



adrenin (ad-ren'in) : hormone secreted by the ad- 

 renal glands, bringing about many changes 

 in the body which help an animal in an emer- 

 gency. 



agar-agar (ah'gar) : gelatin-like product of certain 

 seaweeds used in raising bacteria. 



agglutinin (ag-glu'tin-in) : antibody which causes 

 bacteria to clump. 



air sacs: little thin-walled sacs making up the 

 lungs in higher vertebrates, each connected 

 with a fine branch of the bronchial tubes; for 

 exchange of air. 



albino (al-bine'oh) : person or other animal whose 

 skin, hair, and eyes lack most or all of their 

 pigment ; applied also to plants with a defi- 

 ciency of pigment. 



algae (al'jee) : plants of the thallophyte phylum 

 which have chlorophyll. 



alimentary (al-i-men'tary) canal: food tube in an 

 animal from mouth to anus. 



allergy (al'er-jee) : a state of abnormal sensitive- 

 ness to a particular substance, such as pollen, 

 foods, dust, etc. 



alternation of generations: regular rotation of sex- 

 ual and asexual reproduction in the life cycle 

 of an organism; mostly in plants. (Both steps 

 are necessary for the production of organisms 

 of the same general appearance as the par- 

 ents.) 



amino (am-ee'no) acids: complex compounds 

 made by plants which, when chemically 

 united in various combinations, make up the 

 proteins of all organisms; also the end prod- 

 ucts in protein digestion. 



amphibians (am-fib'i-ans) : members of a class 

 of vertebrates with soft, naked skins, usually 

 breathing by means of gills in their early 

 stages; in later stages, breathing by means of 

 lungs. 



amylase (am'i-lace) : one of several starch-split- 

 ting enzymes. 



anaesthetic (an-es-thet'ic) : something that causes 

 a general or local loss (or partial loss) of 

 pain or other sensation. 



anatomy (an-at'o-me) : study of the structure of 

 plants and animals. 



anemia (an-ee'me-a) : condition in which there is 

 a deficiency of hemoglobin; often accompa- 

 nied by a reduction in the number of red 

 blood cells. 



angiosperms (an'jee-o-sperms) : plants of the 

 spermatophyte group with seeds lying in an 

 ovary; true flowering plants. 



annelids (ann'ell-ids) : members of a phylum of 

 invertebrates which have ringed or segmented 

 bodies, such as the earthworms. 



annual (an'you-el) : plant that lives for only one 

 growing season. 



annual ring: easily distinguished ring forming 

 each year in the woody tissue of dicot trees 

 and shrubs through the growth of cambium 

 cells. (The number of rings gives the age of 

 the stem.) 



anoxia (an-ox'ia) : condition in which the body 



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