GLOSSARY-INDEX 399 



endoparasites. Parasites living within the body of their host, 231. 

 endoplasm (Gr. endon = within + plasma = substance). The inner 



layers of protoplasm in the Protozoan cell, 54, 62. 

 end organs. Special organs at the ends of the nerves, 211; peripheral and 



central end organs are recognized, 

 enemies, relation of animals to, 382. 

 energy, 292; stored by plants, 299. 

 English sparrow, 345. 

 enteron. The alimentary canal, 158. 

 entire. Of a leaf margin, without indentations, 

 environment. The surroundings which influence organisms, 351. 

 enzymes. Substances secreted by organisms and having powers of fer- 

 mentation; unorganized ferments, 306. 



epiblast. A name applied "to the ectodermal layer of the embryo, 

 epidermis (Gr. epi = upon -f- derma = skin). The outer layers of cells 



of any organism, 104, 115, 167, 176. 

 epiglottis (Gr. epi = upon -f glottis = glottis) . An elastic lid covering 



the glottis, which prevents food from passing into the windpipe, 

 epiphysis. -Same as pineal gland, 193. 

 epithelio-muscle cells. Cells of the ectoderm of Hydra, with contractile 



fibers extending from their base, 143. 



epithelium (Gr. epi = upon + thele = nipple) . Cell layers covering sur- 

 faces or lining canals or cavities, 169. 

 equatorial plate. The flattened mass of chromosomes formed between 



two centrosomes, 86. 

 erythrocytes (Gr. erythros = red + cytos). The red corpuscles of the 



blood, 192, 205. 

 Eudorina, 263. 

 Euglena, 75, 76, 217. 

 Eustachian tubes. The tubes leading from the throat to the middle ear, 



186, 197. 

 eversion (Lat. e = out -f vertere = to turn). The process of turning a 



part inside out. 

 evolution. The theory that traces the origin of the present world from the 



past as the result of the unfolding of natural law, 348. 

 excreta, 139. 

 excretions. Waste products of metabolism eliminated by glands, 56, 139, 



210. 

 excretory system. 56, 62, 139; of earthworm, 161; of frog, 199; of Hydra, 



151; of plants, 225. 

 exoccipital bones, 180. 



