Appendix 855 



Reproduction (re pro -duk' shun) (L. re, again; pro, forth; duco, to lead), pro- 

 duction of offspring. 



Reptile (rep' til) (L. repere, to crawl), a class of vertebrates which ordinarily 

 crawl, as snakes, turtles, lizards, etc. 



Respiration (res pi -ra' shun) (L. re, again; spiro, to breathe), exchange of oxy- 

 gen (entering) and carbon dioxide (leaving) in an organism. 



Response, reaction to a stimulus, external or internal. 



Resting cell, one not dividing by mitosis. 



Reticular (re -tik' u lar) (L. reticulum, net), network of fibrils. 



Reticular theory, that protoplasm is physically constructed of networks of fibrils. 



Retina (ret'ina) (L. rete, net), hght-sensitive membrane of the eye to receive 

 images. 



Reversion (re -ver' shun) (L. re, back; verto, to turn), return to an ancestral type 

 or condition. 



Rhabdite (rab' dite) (Gr. rhabdos, rod), rodlike structure in epidermis of certain 

 fiatworms, probably for protection. 



Rheotropism (re -ot' ro pizm) (Gr. rhein, flow; trope, respond), response to water 

 currents. 



Rhizoid (ri' zoid) (Gr. rhiza, root; eidos, like), slender, rootlike filaments in cer- 

 tain lower plants which function as roots. 



Rhizome (ri' zom) (Gr. rhiza, root), underground stem which has the appearance 

 of a root. 



Rhodophyta (ro -dof i ta) (Gr. rhodon, red; phyta, plants), red algae. 



Rodent (ro' dent) (L. rodere, to gnaw), gnawing animal such as rat. 



Root cap, the extreme, protective tip of a root. 



Root hair, fine hairlike extension of the epidermis of plant roots for absorption. 



Rotifer (rot'ifer) (L. rota, wheel; ferro, to bear), small, multicellular, aquatic 

 animal with wheel-like organ of rotating cilia on the anterior end. 



Rudimentary (roo di -men' ta ri) (L. rudis, immature), not fully developed. 



Ruminant (roo'minant) (L. rumen, throat), animal which chews its cud, as a 

 cow. 



S . ' 



Saliva (sa -li' va) (L. saliva, spittle), secretion of salivary glands. 



Saprophyte (sap' ro fite) (Gr. sapros, rotten; phyton, plant), an organism living 



on dead or decaying organic matter, particularly of plants. 

 Sarcolemma (sar ko -lem' ma) (Gr. sarx, flesh or muscle; lemma, covering), cover- 

 ing of a striated voluntary muscle cell. 

 Sarcoplasm (sar' co plazm) (Gr. sarx, muscle; plasma, liquid), the cytoplasm of 



muscle cells exclusive of sarcostyles (fibrils). 

 Sarcostyles (sar' ko stile) (Gr. sarx, muscle; stylos, rod), fibrils in the cytoplasm 



of voluntary, striated muscle cells. 

 Scapula (skap'ula) (L. scapula, shoulder blade), shoulder blade or dorsal part 



of pectoral girdle, 

 Schizomycophyta (skiz o my -kof i ta) (Gr. schizo, fission; mykos, fungus; phyta, 



plants), fission fungi or bacteria. 

 Sclerenchyma (skier -engk' i ma) (Gr. scler, hard; engchyma, poured in), plant 



tissues whose cell walls are thickened for protection and support. 



