826 Appendix 



Crossing over, rearrangement and crossing over of linked characters as a result of 

 exchange of genes between homologous chromosomes during synapsis. 



Crustacea (krus -ta' she a) (L. crustaceus, shell or crust), a class of the phylum 

 Arthropoda characterized by a chitinous exoskeleton. 



Cutaneous (ku -ta' ne us) (L, cutis, skin), pertaining to the skin. 



Cuticle (ku' tik 1) (L. cutis, covering), transparent covering. 



Cutin (ku' tin) (L. cutis, skin) waxy substance covering leaves to make the 

 cuticle impervious to water, 



Cyanophyta (si an -of i ta) (Gr. kyanos, blue; phyta, plants), blue-green algae, 



Cyclosis (si -klo' sis) (Gr. kyklosis, circulate), circulating movement of protoplasm 

 in a cell. 



Cyst (sist) (Gr. kystis, sac), protective covering about an organism. 



Cysticercus (sis ti -sur' kus) (Gr. kystis, sac; kerkos, tail), larval bladderworm 

 stage of certain tapeworms. 



Cytogenic reproduction (si to -jen' ik) (Gr. kytos, cell; gen, to form), reproduc- 

 tion afifected by means of unicellular germ cells which grow and divide to 

 form a multicellular organism (contrast with Somatogenic reproduction). 



Cytology (si -tol' o ji) (Gr. kytos, cell; logos, science), study of cells. 



Cytolysin (si to -ly' sin) (Gr. kytos, cell; lysis, destroy), substance which destroys 

 cells. 



Cytolytic, see Cytolysin. 



Cytoplasm (si'toplazm) (Gr. kytos, cell; plasm, liquid), the portion of the proto- 

 plasm outside the nucleus. 



Cytoplasmic inclusions, nonliving materials in the cytoplasm. 



Cytotoxin (si to -tok' sin) (Gr. kytos, cell; toxicon, poison), substance having a 

 specific toxic efTcct on cells of certain types. 



D 



Dactyl (dak' til) (Gr. daktylos, finger), refers to finger. 



Darwinism, theory of natural selection proposed by Charles Darwin; not synony- 

 mous with organic evolution. 



Deciduous (de-sid'uus) (L. de, away; cadere, to fall), falling off at end of a 

 period of growth. 



Dehydration (de hi -dra' shun) (Gr. de, from; hydros, water), extraction or re- 

 moval of water. 



Deltoid (del' toid) (L. delta, triangle), triangular, like the deltoid muscle. 



Dendrite (dendron) (den' drit) (Gr. dendron, tree), branched processes which 

 carry impulses toward the nerve cell (neuron) (contrast with Axon). 



Denitrifying (de -ni' tri fy ing) (Gr. de, from; nitrogen) , break down of nitroge- 

 nous substances. 



"De novo," a Latin phrase denoting an origin from no known source or from no 

 similar structure. 



Dentine (den' teen) (L. dens, tooth), inner part of tooth. 



Dermis (derma) (der' mis) (Gr. derma, skin), true skin underlying the epidermis 

 (same as corium). 



Determinate cleavage, early divisions of an ^gg in which each blastomere can be 

 traced to some future tissue or organ and in which the original cells are 

 arranged along the various axes of the organism. 



