TENOPYR: CONSTANCY OF CELL SHAPE 69 
relatively only two-thirds to three-fourths as wide as is usual. 
Such leaves also were examined. 
Measurements were made of the cells of the lower epidermis of 
such leaves of P. lanceolata, as well as those of the normal P. lan- 
ceolata and P. major leaves. Also the palisade cells of the two 
species of plantain leaves were compared. The results of these 
measurements are given in cell size and:in cell number per milli- 
meter in TABLE VI. 
TABLE VI 
PLANTAGO 
Measurements of the length and the width of the leaves of two species of plantain, 
and of the corres ponding dimensions of the cells of their lower epidermis and their palisade 
tissue in transverse section, expressed in millimeters and in number of cells to one milli- 
meter. B = average size of cells in mm. C = average number of cells to 1 mm. 
Numerals in parentheses show the number of counts. 
Leaf ell £7 pi A ‘mi: 
Length Width Length Width 
POI 6 i 176.09 110.06 B(100), 0.031 0.044 
C(100), 30.09 22.63 
MOG. Se ge po Bia hs I Ry A Srp WE 
Ps hanceolatin 05 ee 310.3 32.63 B(100), 0.035 0.041 
C(100), 27.97 23-97 
Pt eG or a ee. D2 fe I ee Ee 
P. lanceolata (narrow).. 153-5 10.5 B(100), 0.032 0.038 
C(100), 30.71 25.81 
Wate oe cs ee ay oe 14.6% I Ke 
Leaf Palisade sae 
Length Width Length Width 
FM ee 48. 27. B(30), 0.022 0.021 
C(30), 44.1 46.28 
Mao... ele ey 3 eer I 1.04: 
FP faneedlete.. eo i eae 70. 23. B(30), 0.021 0.021 
C(30), = 92 46.79 
Mat eee ot eee 3-04 I SE 
In both species the palisade cells are quite round in transverse 
section. The cells of the lower epidermis of P. major are slightly 
shorter than those of P. lanceolata, but the disproportion does not 
approach that between the length and width of the leaves of the 
two species. The P. lanceolata cells are only 7 per cent. longer and 
6 per cent. shorter than those of P. major. 
I have plotted frequency curves for each species showing the 
number of times that a given ratio of the length to the width of 
the epidermal cells occurred. It would be difficult to determine, 
