■■] 



JENNINGS— HEREDITY IN PROTOZOA. 



405 



was I20 microns in length. It was allowed to propagate in a culture 

 free from all other Paramecia, from April 9 to June 11 (thus a little 

 more than two months). Now a random sample gave the polygons 

 shown at c, Diagrams i and 2 ; the measurements are given in Table 

 IV. This group corresponds very closely to the smaller group a of 



Table IV. 



Correlation Table for Length and Breadth of a Random Sample Descended 



from the single small Individual c, taken from Culture i and allowed 



to Multiply 63 Days. (See Polygons c. Diagrams i and 2.) 



Length in jMicrons. 

 c 104 108 112 116 120 124 128 132 136 140 144 148 152 156 



5 



24 

 39 

 23 



9 



Length— IMean, 130.120 ±: .6281" 



St. Dev., 9.284 ± .443/^ 



Coef. Van, 7.134 ± .342 



Breadth — -Mean, 



St. Dev., 

 Coef. Var., 



36.280 ± .26oAt 

 3.8B0 ± .1841M 

 10.700 ± .516 



Mean Index or Ratio of Breadth to Length, 27.913 per cent. ; Coef. Cor., 

 .5208 ± .0492. 



the original culture, though with slight differences in breadth. 



4. A single very large specimen, D, approximately 250 microns 

 in length, was isolated from the original culture on April 12 and 

 allowed to propagate freely till June 11 (two months) : 100 speci- 

 mens taken at random then gave the measurements shown in the 

 polygon D, Diagrams i and 2, and Table V. 



Examination of the polygons and tables shows that the two 

 forms retain their essential characteristics when isolated and propa- 

 gated. The results showni in the diagrams are typical of many 

 others. I have kept distinct strains of each of these groups for 

 periods (at the present time) of more than eighteen months, and 

 measurements made at frequent intervals during that time show that 

 they have always remained quite distinct. 



Thus it is clear that these colorless Paramecia fall into two dis- 

 tinct groups, wdiich are at least relatively permanent. As is well 

 known, two species of colorless Paramecia have long been distin- 



