Appendix 859 



Surface tension, greater tension (attraction) of the surface molecules of liquids 



for each other than the attraction of molecules beneath the surface. 

 Suspension, particles not dissolved but suspended in a fluid. 

 Suture (su' tur) (L. suo, to sew), junction of two bones, usually an irregular, 



serrated line. 

 Swimmerets, paired, branched appendages beneath the crayfish abdomen and just 



posterior to the walking legs. 

 Symbiosis (sim bi -o' sis) (Gr. syn, together; bios, living), two different species of 



organisms associated for mutual benefit. 

 Symmetry (sim' e tri) (Gr. syn, together; meton, measure), having similar parts 



or regularity of form. 

 Sympathetic nervous system, see Autonomic system. 

 Synapse (sin'aps) (Gr. syn, together; hapto, unite), space between axon brush of 



one nerve cell and dendrite of next nerve cell. 

 Synapsis (si -nap' sis) (Gr. synapsis, union), temporary conjunction of the pairs 



of homologous chromosomes (from male and female parent) previous to 



the maturation of germ cells. 

 Syncytium (sin -sit' i um) (Gr. syn, together; kytos, cell), undivided mass of pro- 

 toplasm with several nuclei, as in certain muscles, fungi, etc. 

 Synergid (si -nur' gid) (Gr. synergos, working together), two small cells near the 



egg at the micropyle end of the embryo sac in an ovule. 

 Syngamy (sin' ga mi) (Gr. syn, together; gamos, marriage), union of male and 



female gametes (sex cells) to form a zygote. 



Tactile (tack' til) (L. tongere, touch), concerning stirnulation by contact. 



Taenia (te'nia) (L. taenia, ribbon), tapeworm. 



Tarsus (tar'sus) (Gr. tarsos, flat), ankle bone or the terminal segment of insect 

 leg. 



Taxis (tack' sis) (Gr. taxis, arrangement), tropismal response involving movement 

 of the organism as a whole. 



Taxonomy (taks -on' o mi) (Gr. taxis, arrangement; nomos, law), scientific classi- 

 fication of organisms. 



Telegony (te-leg'oni) (Gr. telos, end; gonio, generation), the unproved theory 

 that mating of a female with a certain male will affect the future off- 

 spring of that female even when sh"e is mated to a different type of male. 



Teleology (tel e -ol' o ji) (Gr. telos, end; logos, study), philosophical study of the 

 final purposes and causes of things which imply the existence of a design 

 in Nature. 



Telophase (tel'ofaz) (Gr. telos, end; phais, appear), final stage in mitosis when 

 daughter cells are formed. 



Tendon (ten' don) (L. tendo, stretch), connective tissue to connect muscle to bone. 



Tentacle (ten'takl) (L. tento, touch), flexible appendage for movement, grasp- 

 ing, etc. 



Terrestrial (ter -res' tri al) (Gr. terra, earth), pertaining to land. 



Test (L. testa, shell), hard, outer shell of such animals as sea urchins. 



Testis (tes' tis) (L. testis, Xcsiis) , male gonad for forming sperm. 



Thalamencephalon (thai a men -sef a Ion) (Gr. thalamos, receptacle; engkephalon, 

 in brain), part of vertebrate brain derived from the embryonic forebrain. 



