376 MR. S. LE M. MOORE’S STUDIES 
On the Lateral Position of the Chlorophyll of Palisade-Cells. 
An interesting problem is propounded when it is asked, What 
is the reason that we find the chlorophyll of palisade-cells ranged 
upon the sides at ordinary grades of illumination? Stahl * 
supposes this to be a method whereby the chlorophyll is with- 
drawn from undue illumination—a doctrine vigorously assailed by 
Haberlandt f, whose idea is that the position of the chlorophyll 
depends upon the form of the cell with this exception, that the 
transverse walls are left free of chlorophyll in order to {facilitate 
the passage of assimilation-products through them. Haberlandt 
bases this notion upon the following chief grounds :— 
(1) That in some types (Ornithogalum nutans, O. umbellatum, 
Muscari racemosum, Scilla bifolia, Viola odorata, Polygonum Bis- 
torta, Ranunculus Ficaria) on cloudy days the transverse walls 
of the palisade-cells are more or less studded with chlorophyll 
grains, which in clear weather and in sunlight move on to the 
sides. 
(2) That if Stahl’s view be correct, we ought to find all those 
cells’ walls parallel to the surface destitute of chlorophyll, and 
all perpendicular, or nearly perpendicular, walls provided there- 
with. This is not the case, since— 
(a) Chlorophyll is sometimes ranged upon the lower transverse 
wall when this abuts upon an intercellular space. 
(b) Cells ending freely in the respiratory chamber without 
reaching the epidermis have chlorophyll upon the free end. 
(c) The cells are sometimes curved, occasionally to such an 
extent, that they become L-shaped ; the septa intervening between 
the cells must obviously be either oblique or vertical when seen 
in transverse section. Now in the horizontal and inclined por- 
tions of these cells the chlorophyll has the same disposition asin 
the vertical part, while the inclined and vertical septa are de- 
nuded of chlorophyll. 
Haberlandt further insists upon the more or less perfect radial 
symmetry of the assimilating tissues of plants with reference to 
the vascular bundles, by which means, together with the absence 
of chlorophyll from the septa, provision is made for the rapid 
transport of assimilated matters to the bundle-sheath. 
* Bot. Zeitung, 1880,-p. 299 &c. 
t Ber. d. deutschen bot. Gesell. 1886, pp. 206-236. 
