igoS.] JENNINGS— HEREDITY IN PROTOZOA. 473 



whole, when the two samples are taken together, greater breadth is 

 associated with less length. 



2. Progeny of c {aiirelia Form). 



With the smaller Paramecia, progeny of the small individual c, a 

 similar series of experiments was undertaken. The individual c 

 came from the same wild culture as D ; its length, as nearly as could 

 be determined in life, was 120 microns. It was isolated April 8, 

 1907. Fig. 3 shows some examples of the descendants of c, drawn 

 to the same scale as the figures of the descendants of D. 



Random Sample. — On June 11 one hundred of the progeny of c 

 gave the measurements shown in Table IV., page 405, the constants 

 being given in row 16, Table XVIII. 



Effect of Adding Boiled Hay. — On August 9 a fairly flourishing 

 culture of the descendants of c was examined, with the results shown 

 in Table LVL, and in row 17, Table XVIII. To this culture a quan- 

 tity of boiled grass was added; this caused rapid multiplication. 

 Twenty-four hours later a sample of 225 specimens was measured, 

 with the results shown in Table XLIX., and row 18, Table XVIII. 

 The added nutrition has caused the mean length to decrease, while 

 the mean breadth remains nearly the same. This is due to the fact 

 that the main effect of the nutrition was to cause rapid multiplication 

 rather than growth in size. The coefficient of variation in length 

 increased greatly, from 9.736 to 15.279, while the variation in breadth 

 remained about the same, though with a slight decrease. This pecu- 

 liar result is mainly due to the fact that the culture after the addition 

 of the grass (row 18) contains many young specimens, which differ 

 from the adults greatly in length, but little in breadth. As usual, we 

 find that an increase in the ratio of breadth to length is accompanied 

 by an increase in the correlation between the two. 



Effect of Fresh Hay Infusion. — The next day (August 11) 

 another lot from the culture shown in Table LVL (row 17, Table 

 XVIII.) was placed in a fresh hay infusion and left twenty- four 

 hours. This nutritive fluid caused the animals to become very 

 plump, while at the same time a moderate amount of fission was 

 induced. The results are shown in Table L., and in row 19, Table 



PROC. AMER. PHIL. SOC. XLVII. I90 EE, PRINTED JANUARY II, I909. 



