582 



INDEX. 



Plankton Continued. 

 enumerative or counting nu-thotl 



of determim'ng, 1 1. 

 gra\imetric nu'tliod of dt'tt-i-niin- 

 in- 1 8. 

 and \olnnietric nietliod of de- 

 determining, combined, 18. 

 ol)litiue-haul method t)f collect- 

 ing, difficulties en- 

 countered in, 1 1, 

 operation of, 2, 10. 

 preservation and examination of, 



17-21. 

 pumping method of collecting, 

 2, 12-17. 

 advantages of, 17. 

 t)perati(-)n of, 16. 

 quantitative examination of, 18. 

 settling and centrifugal methods 

 of volumetric determination of, 

 19, 20. 

 Studies. 1. Methods and Ap- 

 paratus in Use in Plank- 

 ton Investigations at the 

 B i o lo g i cal Experiment 

 Station of the University 

 of Illinois, 1-25. 

 hil)liography in, 22-23. 

 exi»lanation of plates in, 23 



25- 

 Studies. II. ( )n Pleodorina illinoi- 

 sensis, a New Species from 

 the Plankton of the Illinois 

 River, 273-293. 



hibliograi)hy in, 291-292. 



ex}jlanation of plates in, 293. 

 Studies. III. On Platydorina, a 

 New (ienus of the Family 

 \' o 1 \ oc i d if, fro m the 

 Plankton of t li i- Illinois 

 River, 4i() 440. 



explanation of plate in, 440. 



literature cited in, 437. 

 variations in, at Havana, 111., 



Plankton— C't>«/'/;///^(^?'. 



vertical-haul method of collect- 

 ing, 2. 

 inapplicable in Station 

 waters at Havana," 111., 



3- 

 work on the Illinois River and 

 Adjacent waters, scope of, i. 

 Planorbis, O p e r c u 1 a r i a nutans 



found on, 340. 

 Plate, Ludwig, Beitriige zur Natur- 

 geschichte der Rotatorien, 

 cited, 367. 

 on Brachionus bidens, 381. 

 on Triarthra terminalis, 367. 

 Platydorina, 436, 437. 

 A new Genus of the Family \ol- 

 vdcidie from the Plankton of 

 the Illinois River, article on, 

 419-440. 

 associates of, 420 421. 

 caudata, 419, 437. 



arrangement of cells of, 426. 

 characteristic features of col- 

 ony t)f, 423. 

 description of, 421 435. 

 parasite of, 425, 434. 

 si/e of colony of, 422, 425. 

 S])ecitic characters of, 435. 

 type of cells of, 425, 427. 

 colors of, 422. 

 discussion of term colony as a])- 



plied to, 433. 

 explanation of plate in Kofoid's 



article on, 440. 

 generic characters of, 435. 

 literature cited in Kofoid's arti- 

 cle on, 439. 

 loconKJtion of, 430. 

 systematic position and relation- 

 ships of, 433. 

 reproduction of, 432. 

 platvptera eurvptera, Polvarthra, 



367. 

 Polyarthra, 340, 352,354, 355,367. 



