416 GLOSSARY 



Antisep'tic (Gr. anti, against ; sepsis, putrefaction) : a substance which prevents 



the growth of harmful microorganisms. 

 Antitox'in : a substance that neutraUzes a toxin. 

 A'nus (Lat.) : the posterior opening of the food tube. 



Aor'ta (Gr. aorte, from aeirein, to Hft) : the large artery leaving the left ventri- 

 cle of the heart. 

 Append'age : a jointed organ attached to the side of the body. 

 Ar'tery (Lat. arteria, windpipe, artery) : a tube which conveys blood from the 



heart. 

 Asep'tic (Gr. a, not ; septikos, putrid) : free from pus-forming bacteria or other 



harmful organisms. 

 Asex'ual : having no sex. 

 Assimila'tion (Lat. assimilare, to make like) : the converting of digested food 



into living matter. 

 Astig'matism (Gr. a, without ; stigma, spot) : a defect of the eye, caused by 



an irregularity in the curvature of the lens. It results in indistinctness 



of vision. 

 Au'ricle (Lat. auricula, little ear) : a chamber in the heart which receives 



blood. 

 Autonom'ic nervous system (Gr. autos, self ; nomos, province) : a part of the 



nervous system not under control of the will ; the sympathetic nervous 



system. 

 Ax'on : the main elongation of a neuron. 



6 



Bacillus : a rod-shaped bacterium. 



Bacte'ria (Gr. hakterion, a little staff) : microscopic one-celled plants, some of 

 which cause specific diseases. 



Bacteriorogy : a study of bacteria. 



Bast : tough, fiberlike cells composing the inner layer of bark. 



Bile : a fluid secreted by the liver. 



Biorogy (Gr. hios, life ; logos, word or discourse) : the study of matter in a liv- 

 ing state ; the study of plants and animals. 



Blade : the flat portion of a leaf. 



Blas'tula (Gr. blastos, a bud) : a stage in the segmentation of an egg in which 

 the cells form a hollow ball with a wall one layer thick. 



Bud : an undeveloped branch. 



Cal'orie (Lat. calere, to be warm) : a heat unit, namely, the amount of heat 

 required to raise the temperature of one kilogram of water one degree 

 Centigrade. (See note on page 119.) 



Calorim'eter : a machine for measuring heat. 



Cam'bium : the growing layer of a dicotyledonous stem. 



