168 GENERAL BIOLOGY 



entoplasm. The inner, more fluid protoplasm of protozoa. 



enzyme. An active substance secreted by a living cell which 

 has the property, under certain conditions, of bring- 

 ing about changes in other substances without itself 

 entering into the composition of the substance which 

 results. 



excretion. Substances produced in the body as the result 

 of metabolism, which are of no further use to the body. 



excurrent. A pore or tube through which a current passes 

 outward. 



exopodite. The outer terminal segment of a biramous 

 crustacean appendage. 



exoskeleton. The external skeleton or shell. 



ferment. See Enzyme. 



fertilization. The union of a spermatozoon and an ovum. 



fibrillar. Composed of fibers. 



nbro-vascular. Bundles in a plant composed of fibers and 



large vessels through which fluids or gases pass, 

 fission. A division, usually into two parts; the common 



method of reproduction in protozoa. 



flagellum. A long, whip-like, vibratory projection of a cell, 

 function. The appropriate action of any special organ or 



part. 



G 



gamete. A reproductive cell capable of union with another 

 gamete. 



gametophyte. A plant which produces gametes. 



ganglion. A group of nerve cells usually forming a swell- 

 ing in the course of a nerve. 



