450 



Birge — The Crustacea of the Plankton. 



D. retrocurva : 



relations to light, 402; to temperature, 

 358. 



sexual period, 346, 359 



vertical distribution, 402, 407, 445. 

 Dates of freezing and opeaing of lake, 289. 



of observations, 436. 

 Diagrams, method of making, 276, 384, 388, 



390. 

 Diaphanosoma, annual distribution, 347. 



in autumn, 313. 



maximum and minimum number, 445. 



relation to light, 425, to temperature, 358. 



in upper meter, 409. 



vertical distribution, 403, 407, 409, 422, 446. 

 Diaptomus, annual distribution, 319. 



appearance in spring 308, 316, 322, 328. 



autumn numbers, 313, 324. 



food, 353. 



maximum and minimum numbers, 319, 

 325, 439. 



number of eggs, 360. 



rate of sinking, 430. 



relation to light, 425; to temperature, 

 316, 323,360. 



summer numbers, 323. 



in upper meter, 408. 



variation in numbers, 368, 369. 



vertical distribution, 384, 393, 394, 407-416, 

 418, 422, 439. 



winter numbers, 320. 

 Diatoma, 307, 318, 353. 

 Diatoms, sinking of, 417. 

 Diseases, D. hyalina, 338, 398. 

 Dinobryon, 357. 

 Distribution, annual, periods, 202. 



factors affecting, 352. 



horizontal, 366. 



vertical, (See Vertical Distribution). 

 Diurnal movement, 407. 

 Dobersdorfer See, 326, 331. 

 Drown, 386, 423. 



Duration of life, D. hyalina, 336. 

 Eggs, numbers of, 332, 360, 361, 362. 

 Eigenmann, 277. 

 Einf elder See, 352. 

 Epischura, 332, 412, 422. 

 Ergasilus, 332, 413, 416. 

 Eudorina, 357. 

 Fitzgerald, 290, 293, 300. 

 Food, in autumn, 311. 



effect on numbers, 352; on vertical dis- 

 tribution, 419. 



of Cyclops, 355, 430. 



of Daphnia, 346, 353. 



of Diaptomus, 353. 



of Leptodora, 351, 430. 



in winter, 307, 321. 

 Fragillaiia, 307, 318, 353. 

 Freezing of lake, dates, 289. 

 France, 374, 414. 

 Fric and Vavra, 348. 

 Geneva lake, 293, 402, 424. 

 Gloiotrichia, 352, 357, 410. 

 Gravitation, effect on vertical distribu- 

 tion, 429. 

 Green lake, 293. 300, 326, 352, 395, 397, 422. 

 Hensen, 278, 282. 

 Horizontal distribution, 366. 



of Crustacea, 371. 



of Cyclops, 368, 370. 



of D. hyalina, 368, 369, 372. 



of D. pulicaria, 343, 372. 



of Diaptomus, 368, 369. 



of Leptodora, 351, 368. 

 Hydrachnids, 302. 

 Ice, thickness of, 289. 

 Introduction, 274. 

 Leptodora, annual distribution, 313, 350. 



diurnal movement, 410. 



food, 351. 



horizontal distribution, 368. 



relation to temperature, 359. 



reproduction, 351, 359. 



Leptodora: 



size, 352 



swarms, 351. 



vertical distribution, 404. 

 Life, duration of, 336. 

 Light, effect on vertical distribution, 409, 



425. 

 Limnocalanus, 422. 

 Lyngbya, 318, 339, 349, 353, 354. 

 Marsh, 300, 326, 332, 346, 348, 371, 375, 395, 



397, 402, 403, 422, 424. 

 Maximum number, cubic meter, 319. 



faU, 311, 387. 



spring, 308. 



summer, 310. 



See Table IV, p. 313, and Appendix. 

 Melosira, 318. 353. 

 Mendota, Date of freezing, 289. 



size, 276. 



transparency, 427. 

 Meter, cubic, population of , 319, 437. 



upper, population of, 409. 

 Methods, of computing, 275. 



of determining net-coefficient, 279. 



of diagraming, 276, 



of dredging, 277 . 



in temperature observations, 286. 



in vertical distribution, 376. 

 Microsporidia, 338. 

 Minimum numbers, early summer, 309. 



late summer, 310. 



winter, 306. 



See Table IV p. 313. and Appendix. 

 Movement, diurnal, 407. 

 Mud, temperature of , 290. 

 Naaplii, annual distribution, 334. 



in autumn, 313. 



maximum number, 335 . 



relations to temperature, 307, 360. 



relation of numbers of, to adults, 335. 



in summer, 360. 



at thermocline, 417. 



variations of numbers, 335. 



vertical distribution, 405, 410-416, 432. 



in winter, 306, 360. 

 Net, coefficient of, 278. 

 Night, vertical distribution at, 400. 

 Notholca, 307. 



Number, Crustacea, factors determining, 

 352, 385. 



maximum, 302, 319. 



minimum, 303. 



See Crustacea, also Appendix, pp. 436- 

 448. 

 Number of eggs, 332, 360, 361, 362. 

 Observations in winter, 277. 



number of, 274, 288, 377, 436. 

 Oconomowoc lakes, 203, 315, 352, 417, 422. 

 Oecistes, 307. 

 Okauchee lake, 424. 

 Ostracoda, 302. 



Percentile vertical distribution, 384; See 



also the various Tables of Appendix. 



Periodic Crustacea, 304, 358. See the 



genera. 

 Pine lake, 331, 422, 424, 432. 

 Ploen, Lake, 326, 331, 348, 357. 

 Reighard, 278. 

 Reproduction affected by temperature, 359. 



of Chydorus, 349, 364. 



of Cyclops, 291, 327, 329, 359. 



of D. hyalina, 335,361. 



of D. pulicaria, 342, 362. 



of D. retrocurva, 346, 358. 



of Diaphanosoma, 347, 358. 



of Diaptomus, 321, 324, 360. 



of Leptodora, 351, 359. 



in summer, 360, 361 . 



in winter, 291, 306, 307, 309, 321, 329, 335, 

 360, 364. 

 Richter, 295. 

 Rotifers in winter, 291. 

 Schizophyceae, 304, 310, 318, 350. 

 Sinking, rate of, 430. 



