GLOSSARY 



191 



nuclear substance, or in some forms the two celk fuse into one. After 



this exchange or fusion fission occurs, usually more rapidly than before. 

 Contracting or pulsating vacuoles, small, clear spots in a cell, filled with 



a watery fluid. In the living animal these alternately disappear and then 



reappear. 

 Co'nus ar te ri o'sus, a cone-shaped artery connected with the ventricle of the 



heart. 

 Cov'ert, a feather overlying the base of the large feathers of the wing or tail. . 

 Cra'ni um, the skull, particularly that part of it inclosing the brain. 

 Crop, an enlarged portion of the esophagus. 

 Cross fertilization, a form of fertilization in which the male and female 



elements are produced by different individuals. 

 Cms ta'ce a, aquatic, gill-bearing arthropods, with two pairs of antennae. 

 Cu'ti cle, the thin outer skin. 

 Cy'to plasm, the portion of the protoplasm of a cell which is outside of the 



nucleus, less dense than the nucleus and usually taking a lighter stain. 



Den'ta ry, the terminal portion or bone of the lower jaw of vertebrates lower 



than mammals, containing all or most of the teeth. 

 Diaphragm, a muscular partition separating the abdomen and thorax, in 



mammals. 

 Dig'i ti grade, walking on the toes. 

 Di oe'cious, reproductive organs in different individuals. 

 Dip'te ra, insects with two wings, including flies, mosquitoes, etc. 

 Dis'tal end, the free end of any object which is attached by one end. 

 Dor'sal surface, the upper surface; the back. 

 Du'o de'num, the first portion of the small intestine. 



Ec'to derm cells, cells covering the outside of sponges and some other simple 



animals. 

 Egg cell, the large, non-motile reproductive cell, with which a sperm cell 



fuses. 

 Em bry on'ic, development within the egg or in the body of the mother. 

 En'do derm cells, cells lining inner cavities in the many-celled animals. As 



a rule they have cilia or flagella. 

 E soph'a gus, the portion of the alimentary canal connecting the mouth (or 



the pharynx) with the stomach. 

 Eu sta'chi an (eu sta'kian) tube, a passage between the pharynx and the 



middle ear. 

 Ex ha 'lent, flowing or moving away from the body. 

 Ex'o skel'e ton, an external skeleton. 

 Eye stalk, an appendage which bears an eye on its iree end. 



