190 LORANDE LOSS WOODRUFF AND HOPE SPENCER 



life-history of Spathidium was done by Moody*' in 1912, and her 

 study is accordingly the point of departure for the discussion 

 of our own observations. 



MATERIAL AND METHODS 



The original animal of the pedigree cultures which we are 

 conducting was isolated on November 5, 1920, from a jar of 

 decaying vegetable debris collected at New Haven. Up to the 

 present time a large number of separate lines have been started 

 from the original one, some in which conjugation has been pre- 

 vented and others in which it has been allowed to occur. 



The various pedigreed lines have been carried on depression 

 slides kept in large moist chambers. The culture medium, 

 which was supplied daily at the time of isolation, consisted of 

 'two drops of standard beef extract^ plus a drop of hay infusion 

 which had previously been seeded with small ciliates, chiefly 

 Colpidium. The bacteria which developed afforded food for 

 the small ciliates and these in turn provided food for the Spathidia. 



The normal living animals, specimens stained intra vitam, 

 preserved total preparations, and serial sections have been studied 

 both with the monocular and binocular compound microscope 

 with various lens systems, including the Zeiss 2-mm. apochromat, 

 and compensating oculars 4 to 18. The Zeiss binocular dissect- 

 ing microscope, with lens combinations affording magnifications 

 up to 172 diameters, has also been employed. 



For fixation, Schaudinn's solution (two parts saturated solu- 

 tion of corrosive sublimate and one part of absolute alcohol) 

 proved most satisfactory for general cytological studies. In 

 special cases osmic-acid vapor, Zenker's fluid, corrosive-acetic, 

 Worcester's fluid, picric acid, and various other fixatives were 

 utilized. A wide range of stains was used, many of them intra 

 vitam. We may mention Lyon's blue, methylene blue, methyl 



* J. E. Moody, Observations on the life history of two rare ciliates, Spathidium 

 spathula and Actinobolus radians. Jour. Morph., 1912, vol. 23, p. 349. 



^ L. L. Woodruff and G. A. Baitsell, The reproduction of Paramecium aurelia 

 in a 'constant' culture medium of beef extract. Jour. Exp. ZooL, 1911, vol. 11, 

 p. 135. 



