MICHIGAN ACADEMY OF SCIENCE. 



•JCm 



peiulicular lines on the cui've are proportional to the staiulard deviation for the 

 ratios calcuiatecl at each node. The nodes are inimhered liorizontally and the 

 latios indicated vertically. Plate XII, figs, a and li. are of type and rogue 

 plants, respectively, about one week before the nicasurements were made. 

 Plate XIII shows a comparable hybrid plant. 



Considering the frequency distributions at each node separately in (be 

 case of the hybrid and the Rabbit-Ear parent, it is seen that (be variability 

 in (bo ratios is of the normal type. In going from the lower to the upper parts 

 of the plant there is a shift in the mean. In the hybrid the change is a pro- 

 gressive one toward the condition found in the Rabbit-Ear rogue. At the 4th 

 node of the rogue the mean is 2.0 and at the 9th node it has increased to 2.5. 

 In the type plant there is very little difference in the mean between the lower 

 and upper parts, the mean being 1.70 and 1.75 for the -Ith and 9th nodes, 

 respectively. The hybrids show a greater variability than either parent in 

 this respect, beginning at the 4th node with a mean ration of 1.72, whicli grad- 

 ually increases until at the 9th node it is 2.4S. 



length of stipule 

 Flc.UltE ;;. Curves olitaiiieil liy ]il(i(tiu.t; lor eadi nuile the mean ratio • 



width of stipule 

 in Itogue, Hyl)ri(l, and Type plants, based on data in Tabh- 't. 'IMu' upper curve is for 

 the Kabbit-Ear Kogue, the middle <-urve for the Hybrid, and tlii' lower for the Type. 

 The perpendicular lines on the curves arc proportional to the value of cr at each node. 

 The lines from the base to a point on the curve indicate the pfisition of the mean for (be 

 plant as a whole. The nodes are indicated liorizontally and tlic ratios vertically. 



At the 4th node the ratio is very close to that of the typo; at the ^th and (ilb 

 nodes it is intermediate between the two parents, and ffoiii (be 7lb to (be 9(b 

 nodes 11 is uinuislMkedly ikmi- IhnI of (lie ro.mie. Comparing (be iilants :is a 

 whole a dillVrent situation might be supposed to exist, as the mean ratio for 

 all nodes of (be hybrid is 2.11S, intermediate between 1.765 for the type 



