GLOSSARY OF IMPORTANT TERMS 



677 



cell, supposed to carry the deter- 

 miners of hereditary qualities. 



Chrysalis (kris'd Us) : the uncovered 

 pupal stage of butterflies. 



Cilium (sil'i um) : a tiny hairlike 

 thread of protoplasm extending 

 from a cell. 



Cloaca (klo a'kd) : the common cavity 

 into which the digestive, urinary, 

 and reproductive systems open in 

 some kinds of vertebrates. 



Coccus (kok'us) : a spherical-shaped 

 bacterium. 



Cocoon (ko koon') : a silky covering 

 around a pupa; the egg-case of 

 spiders. 



Coelenterata (se len'ter a'td) : phy- 

 lum of animals including the corals 

 and jellyfishes. 



Coleoptera (kol'e Sp'ter d) : the order 

 of insects to which beetles belong. 



Communicable disease : a disease 

 that can be passed directly from 

 one person to another. 



Compound eye : an eye made up of 

 many simple eyes or ommatidia. 

 Insects have compound eyes. 



Conjugation (kon'joo ga'shwn) : the 

 temporary union of two sex cells of 

 equal size, with a fusion of nuclei 

 and interchange of nuclear ma- 

 terial. 



Connective tissue : collections of cells 

 which support and connect other 

 tissues. 



Conservation : preserving or protect- 

 ing. 



Contractile vacuole : a small cavity, 

 found in the cytoplasm of many 

 protozoans, which appears and dis- 

 appears with regularity. It is be- 

 lieved to be an organ of excretion. 



Corolla (ko rol'd) : the petals of a 

 flower taken together. 



Corpuscles (kor'pus'ls) : the red and 

 the colorless cells in the blood. 



Cortex (kor'teks) : a fleshy portion of 

 the root, outside the central cylin- 

 der ; the inner layer of bark. 



Cotyledon (kot'I le'dwn) : leaf of an 

 embryo, in a seed. 



Cross-pollination : taking pollen from 

 the anther of one flower and placing 

 it on the stigma of another flower. 



Crustacea (krtis ta'she d) : class of 



animals including the lobsters, cray- 

 fish, and crabs. 



Culture : a growth of bacteria or 

 other microorganisms in a prepared 

 nutrient medium. 



Cycad (si'kad) : family of tropical 

 gymnosperms. 



Cyst (sist) : a hard sac or capsule in- 

 cluding a one-celled animal in its 

 resting stage. 



Cytoplasm (si'to plaz'm) : the living 

 substance of the cell outside of the 

 nucleus and inside the cell mem- 

 brane. 



Deciduous (de sid^u us) : falling off at 

 maturity. w 



Dehiscent (de hls'ent) : opening along 

 a definite line to discharge contents. 



Dendrites (den'drits) : delicate proto- 

 plasmic branched endings of a 

 neuron. 



Dentine (den'tin) : material compos- 

 ing the main part of a tooth. 



Dermis (dur'mis) : the layer of skin 

 below the epidermis. 



Diaphragm (dl'd fram) : the muscular 

 partition between the thorax and 

 the abdomen. 



Diastase (di'd stas) : an enzyme 

 formed in plants which changes 

 starch to grape sugar. 



Dicotyledon (dl kot'i le'dun) : a plant 

 that bears seeds having two cotyle- 

 dons. 



Diffusion : the passage of particles of 

 a substance, either gas or liquid, 

 from a point of greater to a point of 

 lesser concentration. 



Digestion: the process of preparing 

 food for absorption. 



Dihybrid. Mendelian term for a 

 cross between organisms which 

 differ in two pairs of alternative 

 characters. 



Diptera (dip'ter d) : an order of insect 

 having two wings, as the flies. 



Disease : a state in which part of the 

 body does not function properly. 



Disinfectant (dis'in fSk'tdnt) : some- 

 thing which kills bacteria. 



Dominant : a Mendelian term applied 

 to that unit character which stands 

 out to the exclusion of the other or 

 recessive character. 



