380 INDEX-GLOSSARY. 



Hypoblast (vvo; /SXao-ros, a growth) The endoderm of a developing em- 

 bryo, 27. 



Hyposkeletal, of muscles Taking origin within the endoskeleton, 208. 



Hypostome (UTTO; <rro/ia, the mouth), in Hydra The conical projection at 

 the end of which the mouth is placed, 19. 



Hyracoidea, 346. 



I 



Ice age, 348. 



Ichthyopsida (ix^ s a fish j ovjns, an appearance), 342. 



Ileum (<\\o>, I twist; iXeos, eiXtos, colic), in the small intestine The part 

 succeeding the duodenum, 286. 



Impregnation. See Fertilization. 



Incubation, 257. 



Infundibulum (infundibulum, a funnel) (1) A ventral projection of the 

 thalamencephalon, to the end of which the pituitary body is united, 

 168, 210, 253, 301 ; (2) in Mammalia One of the vesicles in which the 

 bronchial tubes end, 294. 



Infusoria, 339. 



Ingestion (ingero, ingestum, carry in) The taking-in of solid food-particles, 9. 



Insectivora, 346, 349. 



Insertion, ~6f muscle The end attached to a relatively movable part, 91. 



Inspiration The in-breathing of air, 129, 204, 249, 294, 316. 



Intelligence, 333. 



Intercellular Situated between cells, 61. 



Interstitial In the interstices between cells, 21. 



Intestine The part of the alimentary canal in which* digestion is completed, 

 29, 49, 57, 78, 94, 113, 125, 141, 160, 190, 242, 286. 



Intracellular Within the cell, 24, 31, 61, 80, 209. 



Intrinsic, of muscle of any part With origin and insertion within that 

 part, 91, 208. 



Intussiisception (intus, inside ; suscipio, susceptum, take up) The inter- 

 calation of new particles between pre-existing ones, 6. 



Invagination The process by which a part originally external becomes 

 internal, 38, 148, 224. 



Invertebrata, 135. 



Iris, 174, 221. 



Irritability, 319 Amceba, 11 ; Vorticella, 16 ; Hydra, 25 ; 319. 



Islands, 348. 



Island of Reil, 338. 



Iter The ventricle of the mid-brain ; the Sylvian aqueduct, 169. 



