196 WILBER BROTHERTON, JR., AND H. H. BARTLETT 
cells (undivided, divided, and taken at random), (2) for cells taken at 
random, whether undivided primary cells or secondary cells, and (3) 
Fig. I. Epidermis from epicotyl of Phaseolus multiflorus, grown in the light. 
(Material chosen from a section in which the primary cells were of the same mean 
length as those of the whole internode.) 
Fig. 2. Epidermis from epicotyl of Phaseolus multiflorus, grown in the dark. 
(Material chosen from a section in which the primary cells were of the same mean 
length as those of the whole internode.) 
for secondary cells alone. The measurements of undivided primaries 
proved to be remarkably interesting, for they tend to indicate that in 
