THE STRUCTURE, LIFE HISTORY, AND INTRA- 



GENERIC RELATIONSHIPS OF PARA- 



MECIUM CALKINSI, SP. NOV. 



LORANDE LOSS WOODRUFF, 



OSBORN ZOOLOGICAL LABORATORY, YALE UNIVERSITY. ^ 

 (SEVEN FIGURES.) 



The term Paramecium was coined by Dr. John Hill of London 

 in 1752 for a group of animalcules comprising "four species," 

 two of which probably include members of the genus Paramecium 

 as recognized today. 1 Then O. F. Miiller in 17732 named an 

 organism Paramcecium aurelia, and in I786, 3 in the first compre- 

 hensive attempt to classify scientifically microscopic animals, 

 definitely established the genus Paramecium and included under 

 it five species. Unfortunately, however, without the slightest 

 warrant etymological or otherwise, Miiller changed the spelling 

 of Paramecium to Paramcecium. Among the species which 

 Miiller distinguished are Paramcecium aurelia and Paramtzcium 

 versutum. The former apparently is Hill's "species 3" and either 

 the present-day P. aurelia or P. caudatum. Paramacium ver- 

 sutum possibly is Hill's "species i" and apparently the present 

 species P. bursaria. M tiller's othei paramecia have since been 

 relegated to other genera. 



Ehrenberg, in his great monograph on the Infusoria 4 (1838), 

 recognized eight species under the genus and returned to the 

 spelling of Hill with the note "Paramecium ist richtiger als 

 Paramaecium." Among Ehrenberg's species are two true 

 paramecia: Paramecium aurelia, which he assumed to be the 

 P. aurelia of Miiller, and P. caudatum,, which he distinguished 

 from P. aurelia chiefly by the greater attenuation of the posterior 

 end of the animal. Muller's species P. versutum, to which 

 Focke in the meantime 5 had given the name Paramecium bursaria, 

 Ehrenberg placed under the genus Loxodes as L. bursaria. 



1 "History of Animals." London, 1752. 



'"Vermium terrestrium et fluviatilium Historia." Havniae et Lipsiae, 1773- 



" Animalcula Infusoria fluviatilia et marina." Havniae, 1786. 



4 "Die Infusionsthierchen als volkommene Organismen." Leipzig, 1838. 



6 "Ueber einige Organisationsverhaltnisse bei polygastrischen Infusorien und 



Radertieren." Isis, 1836. 



IJI 



