426 GLOSSARY 



cell or cells from a single parent ; in sexual reproduction two cells from 



two plants or two animals of different sexes come together to form a new 



individual. 

 Respira'tion (Lat. re, again ; spirare, to breathe) : taking in oxygen and giving 



out carbon dioxide by living cells. 

 Ret'ina (Lat. rete, a net) : the coat of the eye in which the optic nerve fibers 



terminate. 

 Rhi'zoids (Gr. riza, root) : root-like bodies in fungi and some other plants. 



Sali'va (Lat. saliva, spittle) : the secretion of the salivary glands. 

 Sap'rophyte (Gr. sapros, rotten ; phyton, plant) : an organism which derives 



its nourishment from dead organic matter, as a mold or a mushroom. 

 Sclerot'ic coat (Gr. skleros, hard) : the outer coat of the eye. 

 Secre'tin : a hormone which causes the pancreas to give out its digestive fluid, 

 Secre'tion : material formed by the activity of glands. 

 Seed : a structure formed in a fruit as a result of the fertilization of the egg 



cell. 

 Seg'ment (Lat. segmentum, a piece cut off) : one of a number of serial divi- 

 sions of an animal's body or of an organ. 

 Sen'sory (Lat. sensus, feeling) : having direct connection with any part of 



the seat of sensation. 

 Se'pal : a leaflike part of the calyx or outer circle of parts in a flower. 

 Se'rum : the Hquid part of the blood plasma. 

 Se'tae (Lat. seta, a bristle) : bristles used for locomotion in earthworms and 



other animals. 

 Sex'ual (Lat. sexus, sex) : pertaining to or having sex. 

 Si'phon (Gr. siphon, a tube) : a tube through which water may pass into and 



out from the mantle cavity of a mollusk. 

 Spe'cies : the smallest group of organisms having characteristics in common 



that make them different from all other organisms. 

 Sperm cell : the male sex cell or gamete. 



Spi'nal cord : a cord of nervous tissue lying in the vertebral column. 

 Spir'acles (Lat. spiraculum, breathing hole) : breathing holes in insects. 

 Spirillum (Lat. spira, coil) : a spiral form of bacteria. 

 Spleen : ductless, glandlike organ near the stomach. 

 Spongy tissue : a layer of loosely placed cells in the leaf. 

 Sporan'gium (Gr. sporos, a seed ; angeion, a vessel) : a sac containing spores. 

 Spore : a reproductive cell capable of growing into a mature organism. It 



may be produced sexually or asexually. 

 Spo'rophyte (Gr. sporos, seed ; phyton, plant) : spore-bearing part of a plant. 

 Sta'men : an organ of the flower in which pollen is formed. 

 Stat'ocyst : semi-organs or balancing pits, formed in crustaceans and some 



other animals. 



