338 Scientific Proceedings (130) 



FOURTH BOTTLES 



I ~~ 9 348 37 9M 9 437 165 27A 9jT 



III 6 207 19 8.42 4 161 63 28.1 5.9 



I-III 22 672 73 9.80 18 798 322 28.7 13.16 



Group I was treated for 3 min., 17 see. and Group III for 20 hrs., 20 min. 

 Group II, not recorded separately in table, but included in the totals. Group 

 I-III was treated for 2 hrs., 15 min. and gave results similar to those re- 

 corded for the other groups. All the groups received approximately the same 

 dose, i.e. y total radient energy. The females, control and X-rayed, remained 

 for three days in each bottle. 



163 (2123) 



Paramecium polycaryum, sp. nov. 

 By LORANDE LOSS WOODRUFF, and HOPE SPENCER. 



[From the Osborn Zoological Laboratory, Yale University, 

 New Haven, Connecticut.] 



The several species of the genus Paramecium naturally fall 

 into two groups: one with the general cell form represented by 

 P. aurelia, P. caudatum, and P. multimncronucleata (aurelia 

 group), and the other by P. bursaria, P. putrinum and P. cal- 

 kinsi (bursaria group). Within each of these groups the species 

 are distinguished chiefly by micronuclear structure and number. 

 One type of micronuclear structure (caudatum type) occurs in 

 P. caudatum and P. bursaria, and P. putrinum; the other (aurelia 

 type) in P. aurelia, P. multimicronuclcata and P. calkinsi. Species 

 with the "caudatum type" possess a single micronucleus while 

 those with the "aurelia type" possess two (P. aurelm, P. cal- 

 kinsi) or several (P. multimicronuclcata)} 



The present paper records the discovery, on November 29, 

 1922, in some material collected in Louisiana, of a Paramecium 

 characterized by the general body form of the "bursaria group" 



i L. L. Woodruff, Biol. Bull., 1921, xli; Proc. Soc. Exp. Biol, and Med., 

 1921, xviii. 



