INDEX 



XI 



Wood, in roots, 115; in stems, 119; 

 uses of, 418 f., 421, 549 f. ; con- 

 servation of, 553 ff. 



Work, changing conditions of, 379 ff. ; 

 fatigue and, 384 ff . ; hours of, 386 f . ; 

 healthful, 406 ; skilled and un- 

 skilled, 406 f. ; related to health 

 promotion, 407 ff. 



Worms, 332 ff.; economic value of, 450 



Worry, 387 



Wounds, treatment of, 187 f. 



Xylem (zilem), 119 



Yeast, 417, 433 



Yellow fever, 324 f. ; reduction of, in 



Cuba, 326; cause of, 449 

 Young, protection of, 488 f. See also 



Development, Infancy 



Zy'go spore, 471 

 Zy'gSte, 471, 472, 473 



