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GLOSSARY 



and a stimulator of gastric secretions; 

 found in all plants and animals. 

 His'to-gen"e-sis (Gr. histos, tissue; gignes- 

 thai, to be born). The origin, develop- 

 ment, and differentiation of tissues 

 from undifferentiated cells of the em- 

 bryonic germ layers. 

 His-toro-gy ( Gr. histos, tissue; logos, study) . 

 The study of the microscopic structure 

 of tissues and organs. 

 Horo-zo"ic (Gr. holos, whole; zoion, ani- 

 mal ) . Nutrition involving the ingestion 

 and digestion of organic material. 

 Ho-moro-gy (Gr. homos, same; logos, 

 study). The study of organs which re- 

 sult from common embryonic origin. 

 They may or may not have the same 

 function. 

 Ho'mo-zy"gote (Gr. homos, same; zeugon, 

 yolk). An organism formed from gam- 

 etes containing like genes for a given 

 character. 

 Hor'mone (Gr. hormon, from hormaein, to 

 arouse or excite). Chemical substance 

 produced by an endocrine gland which, 

 when transported to another area, pro- 

 duces a specific effect. 

 Host (L. hostis, stranger). The organism 



upon which a parasite lives. 

 Hy'a-line (Gr. hijalos, clear). A translucent, 



albumenoid material. 

 Hy'brid (L. hybrida, mongrel). An organ- 

 ism formed from the union of gametes 

 differing in one or more genes; a heter- 

 ozygote. 

 Hy'dranth (Gr. hydra, water serpent; an- 

 thos, flower). A vegetative branch of 

 a hydroid colony. 

 Hy'dro-car"bon (Gr. hydor, water; L. 

 carho, coal). An organic compound 

 formed only of hydrogen and carbon. 

 Hy-drd'y-sis (Gr. hydor, water; lysis, a 

 loosing). Chemical decomposition by 

 reaction with water. 

 Hy'oid ( Gr. hyoides, Y-shaped ) . A Y-shaped 

 group of bones at the base of the 

 tongue. 

 Hy'per-ton"ic (Gr. huper, beyond; tonikos, 



strength). High osmotic pressure in 

 reference to another solution. 



Hy-poph'y-sis (Gr. hupo, under; physis, 

 growth). The pituitary gland. 



Hy-poth'e-sis (Gr. proposal). Tentative sol- 

 ution or proposal concerning a prob- 

 lem. 



Hy'po-ton"ic (Gr. hupo, under; tonikos, 

 strength). A lesser osmotic pressure in 

 reference to another solution. 



I-den'ti-cal twins. Twins arising from the 

 same fertilized egg and therefore hav- 

 ing the same genetic constitution. 



Il'e-um ( L. grain ) . The most posterior por- 

 tion of the small intestine. 



Il'i-um (L. flank). The dorsal bone of the 

 pelvic girdle. 



In"breed'ing. The crossing of closely re- 

 lated animals. 



In-fun-dib'u-lum ( L. infundibidiim, funnel ) . 

 A stalk-like evagination of the dien- 

 cephalon. 



In-gest' (L. ingesttis, from ingcrere, to put 

 in). To take in food. 



In'or-gan"ic (L. in, not; Gr. organikos, in- 

 strument). Pertaining to substances of 

 non-organic origin. 



In-ser'tion (L. insertus, from inserere, to 

 connect, insert). Point of attachment 

 of a muscle to the movable part. 



In'su-lin (L. instda, island). Hormone se- 

 creted by the pancreatic Islets of Lan- 

 gerhans. 



In-teg'u-ment ( L. integitrnenttim, covering ) . 

 The outermost covering of an organ- 

 ism; skin. 



In'ter-cer'lu-lar (L. inter, between; cellula, 

 cells). Between cells. 



In-ter'nal se-cre'tion. Secretion into the 

 blood stream. 



In'ter-sti"tial (L. inter, between; sistere, 

 to set). Pertaining to intercellular 

 spaces. 

 In-tes'tine (L. intestinus, internal). Part of 

 the digestive tract posterior to the 

 stomach. 



