544 JENNINGS— HEREDITY IN PROTOZOA. [April 24, 



CONTENTS. 



' Page 



I. Introductory 393 



II. Preliminary Study of Variation in Paramecium 394 



1. General Methods of Work ; Statistical Treatment and its Uses. 395 



2. A Typical Culture 396 



3. Methods of Measuring and Recording 396 



4. Method of Constructing the Polygons 399 



5. Two Groups of Paramecia 402 



6. Are Differences in Size Hereditary within Each of the Two 



Groups ? 407 



7. Proposed Analysis of the Polygons of Variation 409 



III. Growth in Paramecium 411 



Effects of Growth on a Variation Polygon, p. 411; Material 

 and Methods of Work, p. 414. 



1. Description of the Different Stages of Growth 415 



First Stage: The Young before Separation is Complete 415 



a. The Unseparated Halves before Lengthening has Begun. 417 



(i) The caudatum form (descendants of D), p. 417; 

 (2) the aurelia form (descendants of c), p. 422. 



b. The Unseparated Halves after Lengthening has Begun. 423 

 Second Stage: The Young Immediately after Fission, up to 



the Age of Ninety Minutes 426 



c. Age o to 5 Minutes 427 



d. Age to 19 Minutes 432 



e. Age 18 to 28 Minutes 434 



/. Age 35 to 45 Minutes 435 



g. Age 75 to 90 Minutes 435 



h. Age to 90 Minutes 435 



Third Stage: Three to Five Hours Old 436 



i. Age 3 to 4 Hours 436 



j. Age 4.20 to 5 Hours 436 



f Fourth Stage : Twelve to Eighteen Hours Old 437 



k. Age 12 Hours 437 



/. Age 18 Hours 438 



Fifth Stage : Twenty-four Hours Old 438 



Sixth Stage : Preparing for Fission 439 



Seventh Stage : Fission 443 



m. Beginning Fission 443 



Descendants of D (caudatum form), p. 443; Descend- 

 ants of c {aurelia form), p. 445. 



n. Later Stages of Fission 447 



2. Summary on Growth in Paramecium, with Curves of Growth.. 447 



Method of Constructing the Curves, p. 448; Characteristics 

 of the Curves, p. 451. 



3. Efifects of Growth on the Observed Variations in Dimensions. 453 



Variation at Fission, p. 453; Variation in Conjugants, p. 453. 



