420 BIOLOGY 



Spirogyra, 30. 



splanchnic. Pertaining to the viscera. 



spleen. A good-sized organ lying among the folds of the intestine, 



187. 



spontaneity. Power of producing movements from internal causes, 2. 

 spontaneous generation. The theory that life can arise in some other 



way than from previously existing life; abiogenesis, 10. 

 sporangium (Gr. spora = a seed + angeion = a receptacle). A sac within 



which spores are produced, 100, 270. 

 spores (Gr. spora = a seed). Single-celled reproductive bodies, capable 



of growing into a new plant without fertilization, 16, 59, 79, 81, 239, 



267. 

 sporoblast (Gr. spora = seed -f- blaslos = a germ). A sac in which 



sporozoites are produced, 242. 

 sporophyte (Gr. spora = seed + phyton = a plant). The stage, in a 



plant with alternation of generations, that produces spores, 272, 274. 

 Sporozoa, 241. 

 sporozoites (Gr. spora = seed + zoon = animal). Spores that result from 



the division of fused gametes, 241. 

 squamosal bone, 180. 



stamens. The modified leaves of a flower that produce pollen, 1 19. 

 starch. A carbohydrate with the general formula CeHioO.s, or some 



multiple of this, 8, 129, 134. 

 stereome cells (Gr. stereos = a solid). Cells in the bark with very thick 



walls, 106. 

 stereotropism (Gr. stereos = a solid + trope = a turning). Reaction to 



solid objects, 53. 



sterility. Unfertility, or inability to produce offspring, or hybrids, 268. 

 sterilize. To treat an object so as to destroy all living things in it, 14, 



17. 



sternum, 182. 

 stigma. The roughened surface on the end of a style, for the reception of 



pollen, 120. 

 stimulus. Any force applied to an organism which will produce a reaction, 



43. 



stinging cells, 143. 

 stipules, 114. 

 stomach, 186. 

 stomata (Gr. stoma = mouth). Openings through the epidermis of plants 



through which gas enters and moisture evaporates, 116. 

 stomodaeum, 284. 

 strawberry plant, reproduction of, 244. 



