1909] 



HARRIS— LEAVES OF PODOPHYLLUM 



441 



leaves for the two habitats, we notice that they differ by ten to 

 twenty times the probable errors of their differences. The standard 

 deviations differ by only one and a half to three times the probable 

 errors of their differences. Perhaps the differences between the 

 means of the collections from the two habitats are significant statisti- 

 cally, but I attach no biological importance to the differences, since 

 they may be due merely to some slight local environmental condition. 

 The variabilities certainly do not differ significantly. 



TABLE III 



Podophyllum 



Series of material 



Average and 

 probable error 



Standard deviation and 

 probable error 



VALLEY PARK, MO.*. 



Lower leaf 



Upper leaf 



Difference 



PALOS, OHIO: 



Lower leaf 



Upper leaf 



Difference 



differences: 



Lowei leaf 



Upper leaf 



6.9201k 

 5 .8 9 o± 



+ i.o3o± 



.029 

 .022 

 .036 



6 



5 

 + 1 



. 5 28± 



•i39± 



. 3 8 9 ± 



.029 

 .027 

 .040 



Coefficient 

 of variation 



+ 

 + 



3Q2± .041 



75i± -°35 



.848±.o22 



.666±.oi6 



+ .i82± .027 



• 792± 021 



• 742± .029 

 + .osoi .036 



-r-.056i.030 

 — .076+ .025 



12.25 

 11.30 



+ °-9S 



12.13 



1443 

 - 2.31 



+ 0.12 



- 



Taking now the question (a), that of a differentiation between the 

 upper and lower leaves, we note that the means differ in both cases 

 by about thirty times the probable error of their differences, and that 

 the lower leaf has in both cases about one lobe more than the upper. 

 The standard deviations differ by an amount which can hardly be 

 regarded as significant. The relative variability as measured by the 

 coefficient of variation is in one case higher for the upper leaf and in 

 one case lower. After calculating the constants for the first series 

 of material, I thought that perhaps the variability of the more distally 

 placed leaf would be regularly lower than that of the more proximal 

 one, as Pearl (4) found the variability of the whorls in Ceratophyllum 

 to be. But the second series does not support this idea. 



It may be interesting to compare the variability in the lobing of the 

 leaves of Podophyllum with that of other leaf characters given by 

 Pearson (5). From page 361 I note the following values of the 

 coefficient of variation for leaf characters: 



