GLOSSARY 919 



Regeneration (re jen era'shuii), the replacement of mutilated parts or au 

 entire animal from a portion of one. 



Renal (re'nal), pertaining to the kidney. 



Rennin (ren'in), an enzyme constituent of gastric juice of mammals and 

 capable of coagulating the protein portion of milk. 



Reproduction (re pr6 duk'shun), the production by an organism of others of its 

 kind. 



Respiration (res pi ra'shun), the exchange within an organism of oxygen enter- 

 ing the protoplasm and carbon dioxide leaving it. 



Response (respons'), the reaction of an organism to a stimulus. 



Rete (re'te), a limited meshlike arrangement or network. 



Reticulum (re tik'ti liim), a fibrous or tubular network. 



Retractile (re trak'til), that which can be withdrawn. 



Retrogression (ret ro gresh'vin), going behind or moving backward. 



Rhabdites (rab'dits), special structures found interspersed among the epidermal 

 cells of flatworms. 



Rheotropism (re ot'ropiz'm), response of an organism to mechanical currents. 



Roe (ro), ovary and eggs of fish. 



Rudiment (roo'di ment), partially developed or embryonic structure; usually 

 without function. 



Rugose (rob'gds), possessing many ridges and folds. 



Ruminants (roo'mi nants), animals which chew the cud. 



Saprophyte (sap'rofit), an organism which absorbs nonliving organic matter 



in solution directl}' through the surface of the bod}-. 

 Sarcolemma (stir ko lem'a), the delicate membrane immediately enclosing the 



striated voluntary muscle cell. 

 Sarcoplasm (sar'ko plaz'm), the cytoplasm of muscle cells exclusive of the 



sarcostj'les or fibrils. 

 Sarcostyles (sar'ko stils), cytoplasm fibrils in the structure of cytoplasm of 



voluntary muscle cells. 

 Schizogony (ski zog'o n50> asexual reproduction. 



Sclerotic (skle rot'ik), the dense fibrous outer coat of the vertebrate eye. 

 Scolex (sko'leks), knoblike "head" on anterior proglottid of cestode. 

 Scute (skut), a plate on the ventral side of the body of the snake. 

 Sebaceous glands (seba'shus), small subcutaneous glands, usually connected 



with hair follicles. 

 Sedentary (sed'en ter i), unattached forms which remain in one place. 

 Semen (se'men), fluid which carries the spermatozoa in the males of most 



animals. 

 Seminal (sem'inal), pertains to spermatozoa. 

 Semipermeable membrane (semipur'meabl), one which permits the passage 



of solvents through it but not solutes, unless they dissolve in the 



membrane. 

 Senescence (senes'ens), period of old age and its effects. 

 Septum (sep'tiim), a wall dividing two cavities. 

 Serial homology (serial homol'ftji), presence of structures of similar origin 



and form in different segments of the same animal. 

 Serosa (sero'sa), membrane covering peritoneal surface of internal organs; 



one which secretes a watery fluid. 

 Sertoli cells (ser to'le sels), modified, supporting or nurse cells for forming 



spermatozoa in the testes. 

 Serum (se'rum), the fluid part of the blood which remains after clotting. 

 Sessile (ses'il), attached directly and incapable of locomotion. 

 Seta (se'ta), hairlike spine or bristle, found in animals. 

 Sinus (si'nus), a cavity in a bone or other part, or a dilated vessel or canal. 



