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GLOSSARY OF IMPORTANT TERMS 



Auricle (6'ri k'l) : a chamber in the 

 heart which receives blood. 



Autonomic nervous system : a part of 

 the nervous system not under con- 

 trol of the will; it is sometimes 

 called the sympathetic nervous 

 system. 



Axon (ak'son) : the main elongation of 

 a neuron. 



Bacillus (bd sil'^s) : a rod-shaped 

 bacterium. 



Bacteria (bak te'ri d) : microscopic 

 one-celled plants, some of which 

 cause specific diseases. 



Bacteriology (bak te'rl ol'o ji) : a study 

 of bacteria. 



Bast : tough, fiberlike cells composing 

 the inner layer of bark. 



Biennial (bl en'i a\) : a plant which 

 completes its life cycle in two years 

 — producing leaves the first year 

 and fruit and seed the second. 



Bile : a fluid secreted by the liver. 



Biology (Gr. bios, life ; logos, word or 

 discourse) : the study of matter in 

 a living state ; the study of plants 

 and animals. 



Bivalve : mollusk having shell con- 

 sisting of two distinct parts or 

 valves connected by a hinge. 



Blade : the flat portion of a leaf. 



Blastula (blas'tu Id) : a stage in the 

 segmentation of an egg in which the 

 cells form a hollow ball with a wall 

 one layer thick. 



Bryophyta (bri of'i td) : the phylum of 

 plants to which the mosses belong. 



Bud : an undeveloped branch. 



Calorie (kal'6 ri) : a heat unit, namely, 

 the amount of heat required to raise 

 the temperature of one kilogram of 

 water one degree Centigrade. 



Calorimeter (kal'd rlm'e ter) : a ma- 

 chine for measuring amount of heat 

 in foods. 



Cambium (kam'M «m) : the layer 

 between the wood and the inner 

 bark where growth takes place. 



Capillaries (kap'i la riz) : minute tubes 

 which connect arteries with veins. 



Capillarity (kap'I lar'I ti) : a phenome- 

 non shown by liquids rising in fine 

 tubes. 



Carapace (kax'd pas) : a bony or chi- 

 tinous case covering an animal's 

 back, as the crayfish. 



Carbohydrate (kar'bo hi'drat) : a class 

 of nutrients composed of carbon, 

 oxygen, and hydrogen, having the 

 oxygen and hydrogen in the same 

 proportion as water. 



Carbon : an element found in all or- 

 ganic compounds. 



Carbon dioxide : a gas, a product of 

 the oxidation of carbon. 



Carnivores (kar'ni vors) : an order of 

 flesh-eating mammals, including the 

 cats, dogs, bears, etc. 



Cell : the structural and physiological 

 unit in plant and animal bodies. A 

 small mass of protoplasm in most 

 cases inclosed in a cell mem- 

 brane and usually containing a nu- 

 cleus. 



Cell membrane: the delicate living 

 covering of a cell. 



Cell sap : water, with materials in 

 solution, found in the vacuoles of 

 plant cells. 



Cellulose (sel'u los) : a dead substance 

 found in the walls of plant cells. 



Cephalothorax (set" 'a 16 tho'raks) : an- 

 terior division of body of some 

 animals, consisting of the united 

 head and thorax. 



Cerebellum (ser' e bei'wm) : part of 

 the brain between the cerebrum and 

 the medulla oblongata. 



Cerebrum (ser'e brum) : the anterior 

 part of the brain. 



Chemical compound : a substance 

 formed by the combination of chem- 

 ical elements. 



Chemical element : a simple sub- 

 stance ; one which cannot be broken 

 into simpler substances. 



Chitin (ki'tin) : a hard, nitrogenous 

 substance present in the exo-skele- 

 ton of insects. 



Chlorophyll (klo'ro fil) : the green 

 coloring matter of plants. 



Chloroplasts (klo'ro plasts) : small 

 bodies of protoplasm which contain 

 chlorophyll. 



Choroid (ko'roid) : the middle coat of 

 the eye. 



Chromosome (kro'mo som) : a deeply 

 staining body in the nucleus of a 



