I 7 6 



LORANDE LOSS WOODRUFF. 



It will be noted that the trichocyst apparatus of P. trichium, 

 as decribed by Stokes, and which he emphasized in naming the 

 organism, agrees closely with that in the new species. The one 



essential difference is the form 

 of the exploded trichocysts, 

 which in P. calkinsi have almost 

 the identical structure of those 

 in P. caudatum as described by 

 Khainsky. 22 



The endoplasm of the new spe- 

 cies is characteristically more 

 vacuolated than that of P. aure- 

 lia or P. caudatum when all are 

 bred in the same culture me- 

 dium. On the other hand it is 

 by no means so fluid as in P. 

 bursaria. It is possible to dis- 

 tinguish almost at a glance the 

 new species from the others, 

 merely by the cytoplasmic ap- 

 pearance, when all are mingled 

 together in the same culture. 



The contractile vacuoles, as 

 the figure shows, are two in 

 number, and agree closely in 

 position and form with those 

 typical of P. aurelia, P. cau- 

 datum, and P. bursaria. Herein 

 is a striking difference from P. putrinum with one contractile 

 vacuole at the anterior end and P. trichium in which two con- 

 tractile vacuoles are situated close together near the anterior 

 end. 



The macronucleus presents no diagnostic characteristics, 

 though, as the figure shows, in the culture under consideration 

 it usually is proportionately larger in size than it is in the well- 

 known species of Paramecium. Little emphasis, however, can 



22 A. Khainsky, "Zur Morphologie und Physiologic einiger infusorien," Arch, 

 f. Protistenk., 21, 1910. 



FIG. 4. Paramecium calkinsi, sp. nov. 



