INDEX 581 



Depressor nerve, 568. 



Deviation, angular, 435. 



Dicrotic notch, 545. 



Diffusion of gases, 14. 



Dioptre, 435. 



Dispersion circle, 429, 470, 471, 472. 



Distance, focal, crystalline leus, 450; principal focal, cornea, 



441. 



Distilled water, a chemical stimulus, 163. 

 Drying, 149, 164. 



DuBois-Reymond, molecular theory, 298. 

 Duchenne's points, 127. 

 Duration of stimulus, 138. 



ELASTICITY and extensibility, of a metal spring, 364 ; of a rub- 

 ber band, 364 ; of skeletal muscle, 365. 



Electric fish, 329. 



Electrical units, 35. 



Electrodes, for human nerves, 132 ; indifferent, 111 ; non-polariz- 

 able, 93 ; platinum, 65. 



Electrolysis, 26. 



Electrolytic solution pressure, 32. 



Electrometer, 34. 



Electromotive force, 34, 287 ; demarcation current, 292. 



Electrotonic currents, 323 ; as stimulus, 328 ; negative and 

 positive variation, 325 ; polarization increment, 325. 



Energy, set free in various forms, 10 ; stimulation, and irrita- 

 bility, 7 ; developing, 361. 



Emmetropia, 490; angle of, 464. 



Engelmann's incisions, 534. 



Ergograph, 354. 



Excitation wave, 336 : remains in original fibre, 181. 



Extensibility, 364, 366. 



Extra contraction of heart, 533. 



Eye, artificial, ophthalmoscopic, 489 ; as camera obscura, 437; 

 normal measurements, 461 ; see optical box, 404; reduced, 

 458 ; schematic, 438. 



Extra current in inductorium, 68. 



FATIGUE, 367 ; human muscle, 368 ; polar, 147. 



Fixation, line, 463. 



Focus, conjugate, concave mirror, 427 ; conjugate, convex lens, 



418 ; conjugate, cornea, 444 ; principal, concave mirror, 405; 



principal, construction, 443; principal, convex lens, 416; 



principal, eye, 454. 



Focal distance, concave mirror, 406 ; principal, convex lens, 417. 

 Focal line, 427. 



