912 TEXTBOOK OF ZOOLOGY 



Homolecithal (ho mo les'i thai) (isolecithal), eggs having a uniform distribu- 

 tion of the yolk. 



Homologous (ho mol'ogus), similar in structure and origin, but different in 

 function. 



Homonomous (ho mon'o mus), slight or no differentiation of body segments. 



Homozygote (h5m6 zi'got), a zygote or resulting organism in which the cor- 

 responding genes are alike. 



Hormone (hor'mon), the essential substance of an internal secretion which 

 serves to help in metabolism regulation. Produced by endocrine glands 

 and carried by the blood. 



Hyaline (hi'alin), semitransparent or glassy. 



Hybrid (hi'brid), a cross, or offspring of parents differing in genetical con- 

 stitution. 



Hydrolysis (hi drol'i sis), chemical rearrangement of a substance by combining 

 with water. 



Hydrostatic (hi dr6 stat'ik), a type of organ which regulates the specific 

 gravity of an aquatic animal. 



Hypertonic (hi per ton'ik), possessing greater osmotic pressure than some re- 

 lated substance. 



Hypostome (hi'postom), a conical projection around and below the mouth in 

 coelenterates. 



Hsrpothesis (hipoth'e sis), an idea as it first develops as the result of pre- 

 liminary observation and experiment. 



Ileum (il'eum), the posterior and longest part of the small intestine. 



Ilium (il'ium), dorsal bone of pelvic girdle of terrestrial vertebrates. 



Immunity (imii'mti), freedom of susceptibility to disease. 



Ingestion (in jes'chun), the taking in of food material by an organism. 



Insectivorous (in sek tiv'6 rus), insect-eating animals. 



Inspire (inspir'), the drawing in of water or air in the respiration. 



Instar (in'star), the period between molts in insect development. 



Insulin (in'sulin), a hormone produced by the pancreas and essential to the 



proper metabolism of carbohydrates. 

 Integration (in te gra'shiin), development and correlation to give unity in an 



organism. 

 Integument (in teg'u ment), the outer covering of the body. 

 Intracellular (in tra sel'u ler), within the cell. 

 Intracellular differentiation (in tra sel'u ler dif er en shi a'shun), the presence 



of a variety of cells within one body. 

 Invagination (in vaj i na'shun), the unfolding process by which the primary 



endoderm is withdrawn into the blastular cavity and becomes enclosed 



by the primary ectoderm. 

 Irritability (ir i tabil'i ti), the capacity of protoplasm for _ responding to 



changes in environmental conditions or to external stimuli. 

 Isolecithal (i so les'i thai). (See Homolecithal.) 



Isotonic (i so ton'ik), possessing the same osmotic pressure in related sub- 

 stances. 



Jejunum (jejob'num), the middle division of the small intestine, between the 

 duodenum and the ileum. 



Karyokinesis (kar i 6 ki ne'sis), mitotic cell division. 

 Karyolymph (kar'i 6 limf ), the more fluid material of the nucleus. 

 Karyoplasm (kar'i 6 plaz'm), the protoplasm which constitutes the nucleus. 

 Karyosome (kar'iosom), a "net knot" or a part of the chromatin which 



forms a distinct body in the nucleus. 

 Katabolism (ka tab'6 liz'm). (See Catabolism.) 



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