GLOSSARY-INDEX 405 



inner ear, 198. 



inorganic, 26. 



insertion. The attachment of a muscle farthest from the center of the 



body, 184. 



intercellular (Lat. inter = between + cellular). Lying between the cells, 

 intercellular digestion, 145. 

 internodes. Spaces between the nodes, 

 interstitial cells (Lat. inter = between -f- sistere = to set). Cells in 



Hydra lying between the cnidoblasts and the muscle cells, 143. 

 intestine. The digestive tract from stomach to cloacal chamber, 186. 

 intracellular (Lat. intra = within + cellular). Lying within the cells, 

 intracellular digestion, 146. 

 intussusception (Lat. intus = inside + suscipere = to take up). The 



process of growth by taking material inside the body and incorporating 



it into the body substance, 5. 

 invagination (Lat. in = within + vagina = a sheath). The act of turning 



inward, as when the finger of a glove is pushed into the palm, 

 invertebrate. A name given to all animals below vertebrata. 

 invertion. The splitting of a molecule of cane sugar into two molecules 



of grape sugar, a molecule of water being added in the process, 9. 

 iris. An opaque curtain, containing pigment, covering the front of the 



eyeball, 197. 

 irritability. The power of reacting under the influence of stimuli, 43, 57, 



63, 219. 

 ischia, 182. 

 isolation. The separation of two individuals from the rest of the species 



so that they will breed together, 351. 

 jellyfish. See medusa. 

 joints. Places where bones or other hard movable parts come together, 



176, 184. 



karyokinesis (Gr. karyon = nucleus + kinesis = movement). The proc- 

 ess of cell division accompanied by a peculiar, complicated nuclear 



division; mitosis, 85. 

 karyoplasm (Gr. karyon = nucleus + plasma = substance). 'The liquid 



protoplasm inside the nucleus; nucleoplasm, 32, 49. 

 katabolism, 139. 



kidneys. Glands in vertebrates secreting urea, 199. 

 kinetic energy (Gr. kinetos = moving). Energy in motion; active energy, 



293. 



kingdoms. The two divisions of organisms, animals and plants, 373. 

 lachrymal (Lat. lachryma = a tear). Pertaining to tears, 

 lacteals. Lymph vessels carrying absorbed fat from the intestine, 192. 



