GLOSSARY 385 



Intercellular (in' ter seV u ler). Between cells. 



Interdigitate (in' ter dij' i tale). To dovetail together like the interlocked fingers of 

 the two hands; said of adjoining environments when strips of each project out into 

 the other. , 



Internal respiration {in ter' nal res' pi ra' shun) . The transfer of oxygen from the 

 blood to the surrounding cells; true respiration. 



Internal secretion {in ter' nal se kre' shun). A secretion poured directly into the blood 

 without passing through ducts. 



Intracellular {in' tra seV u ler). Within a cell. 



Invagination {in vaj' i na' shun). The folding of a layer of cells inward into a cavity. 



Invert {in vert'). To hydro lyze (a compound sugar) into a monosaccharide. 



Invertase {in ver' tase). An enzyme splitting cane sugar into glucose and fructose. 



Ion {i' on). An atom or group of atoms bearing an electrical charge, formed by many 

 substances on going into solution. 



Irritability {ir' ri ta Ml' i ti). SusceptibiUty to the influence of stimuli. 



Ischium {is' hi vm) {pi., ischia). The posterior of two ventrally located bones 

 of the pelvic girdle of vertebrate animals above the fishes. 



Isogamete {i' so gam' eet). One of t\. o gametes of equal size which fuse in reproduc- 

 tion. 



Isogamy {i sog' a mi). Fusion of like gametes in reproduction. 



Isomer {i' so mer). One of two or more chemical substances composed of the same 



elements, and of the same number of atoms of each element per molecule. Each 



substance is an isomer of the other (s). 



Isosmotic {i' soz mot' ik). Same as isotonic. 



Isotonic {i' so ton' ik). Having the same osmotic pressure; said, for example, of two 

 solutions. 



Jejunum {jeju' num). The second of three divisions of the small intestine. 



JugtJar vein {ju' gu ler vane'). A large vein returning blood from the head. 



Julus (jV Zms). a genus of milhpedes. 



Jurassic {ju ras' sik). Of middle Mesozoic age; named from rocks in the Jura moun- 

 tains. 



Karyokinesis {ka' ri o ki ne' sis) . Same as mitosis. 



Keratin {ker' a tin). A substance forming the bulk of horn, hair, nails, etc. 



Kidney {kid' ni). The chief organ for the excretion of nitrogenous wastes in most 

 vertebrates. Also an excretory organ in certain other animals. 



Kinosternidae {ki' no ster' ni dee). A family of turtles. 



Labial palp {la' hi al -palp'). One of two pairs of flattened organs beside the mouth of 



mussels. 

 Labium {la' hi um). The lower lip in many animals. 

 Labyrinth {lah' i rinth) . The inner ear of vertebrates. 

 Lactase {lak' tase). An enzyme of the small intestine whose function is the conversion 



of milk sugar (lactose) into dextrose and galactose. 



Lacuna {la ku' na). A space in the matrix of bone which contains in life a bone cell. 



Lamarck, Jean Baptiste, etc. (la marl/). Celebrated French naturalist and proponent 

 of evolution, 1744-1829, 

 25 



