GLOSSARY 611 



telo(t6l'6). G.;end. 



telolecithal (t6l 6 l6s' 1 thai). A term applied to an egg cell with the yolk massed at 

 one pole. 



telophase (tel' 6 faz). The last stages in mitosis, in which the cytoplasm is divided 

 and the nucleus returns to the condition seen in a resting cell. 



tendon (t6n' dun). A mass of white fibrous connective tissue fibers forming an attach- 

 ment for a muscle; adj., tendinous. 



tentacle (tfn'tak'l). A soft elongated, nonarticulated appendage found in a great 

 variety of invertebrates and serving a great variety of functions; a tentacle 

 may be used as a grasping organ, or it may bear sense organs; adj., tentacular 

 (ten tak'ular). 



terrestrial (tgr rgs' tri al). Living on or in the ground; used in distinction from 

 aquatic. 



testis (tgs' tis). The male reproductive organ, in which sperm cells are produced. 



tetanus (t6t' anus). A state of continued contraction in a muscle fiber due to con- 

 stantly repeated stimulation; adj., tetanic (te tan' Uv). 



tetrad (t6t' rad). A chromatic body divided into four parts representing the halves 

 of each of two chromosomes which have united in synapsis and have been preco- 

 ciously divided. 



Thales (tha' lez). Greek philosopher; seventh and sixth centuries B.C. 



therm (thurm). G.; heat. 



thermocline (thiir' mo kiln). A horizontal plane appearing in a deep lake in summer 

 below which the water is stagnant and above which frequent circulation is caused 

 by wind and other agencies. 



thermotropism (ther mOt' r6 piz'm). The response of an organism to a heat stimulus; 

 adj., thermotropic (thCir mo tr6p' Ik). 



thigmo (thig' m6). G.; touch. 



thigmotropism (thIg m6t' ro pIz'm). The response of an organism to a contact 

 stimulus; adj., thigmotropic (thig mo tr6p' Ik). 



thorax (tho' raks). A portion of the body of many animals lying between the head, 

 or head and neck, and the abdomen; adj., thoracic (th6 ras' Ik). 



tissue (tish' u). A mass of similarly differentiated cells. 



tome (tom). G. ; cut. 



tonsil (t5n' sJl). A mass of lymphoid tissue located, in man, one on each side of the 

 passage from the mouth to the pharynx; adj., tonsillar. 



tonus (to' ntis). A state of continual moderate contraction in a nonstriated muscle 

 fiber; adj., tonic (t6n' Ik). 



toxin (t6k' sin). Anj^ substance that acts as a poison in an animal bodj'; adj., toxic. 



trachea (tra' ke a). A tube conveying air into the body for the purpose of respiration; 

 found in many arthropods and in all lunged vertebrates; adj., tracheal. 



traumatism (tro' ma tiz'm). A condition in the body due to a physical injury. 



Trembley, Abraham. Swiss naturalist; 1700-1784. 



trial and error. A method of finding the most favorable condition or environment; 

 in animals possessing intelhgence it is done by conscious experimentation, in 

 lower animals by automatic responses to stimuli due to random sampling. 



trich (trlk). G.;hair. 



trichocyst (trlk' 6 sist). One of many minute elongated sacs in the ectoplasm of a 

 Paramecium and similar protozoans, set at a right angle to the surface, the con- 

 tents of which when thrown out form rodlike bodies used as weapons of defense 

 and perhaps of offense. 



trUiybrid (tri hi' brid). An offspring of parents differing by three characters. 



triploblastic (trip 16 bias' tik). Having three germ layers. 



trocho (trok' 6). G.; a wheel. 



