TRANSACTIONS OF SECTION K. 767 
graviperception; and, as a fact, the seedling is gravisensitive throughout, but is 
especially so at the apex. If this is not the meaning of the statoplasts we must 
find some other. For instance, are the loose starch-grains connected in an 
unknown way with heliotropic sensitiveness, which often has the same distribution 
as that of graviperception? Or is the looseness of starch connected in some way 
with food storage? Is it to allow of starch being closely packed in part of the 
cell, leaving the rest of the space free ? 
Again, the most striking general fact about the distribution of falling starch is 
its presence in the endodermis.' If we believe that the endodermis is essentially 
a tissue of gravisensitive cells we can understand the striking fact that it contains 
loose starch only as long as the stem is capable of growth curvature.” Otherwise, 
the theories of the function of the endoderm, which have never been very satis- 
factory, have the additional burthen of explaining this last-named fact. 
According to Haberlandt (00), some monocotyledons whose leaves contain no 
starch have falling grains in the endodermis. Némec (01, p. 24) quotes from 
Sachs the case of Alliwm cepa, where statoplasts occur in the root-cap, the 
endoderm, and punctum of the seedling, and not elsewhere. Then we have 
oceurrence of starch in the pulvinus of grasses and not in the rest of the haulm, 
Viscum is not geotropic, and has no statoplasts. In the holdfast roots of Hedera 
and Maregravia there is no starch, and in Hoya, Pothos, and Ficus the starch is 
not movable, and these roots are not geotropic.* 
Jost (02) brought forward, as a serious objection to the statolith theory, the fact 
that tertiary roots possess statoliths, but are not sensitive to gravitation. This 
objection has been overcome by the discovery * that when the primary root is cut 
off and a secondary assumes its place and manner of growth, the tertiaries springing 
from it are diageotropic, and thus have at least an occasional use for their 
statoplasts. 
I have shown® that the cotyledon of Setaria and Sorghum is the seat of gravi- 
perception, and it is there that the statoplasts are found.® Wiesner (02) was 
unable to find statoliths in the perianth-segments of Chivia nobilis, which are 
geotropic, nor in those of Chivia miniata, which are not geotropic. Here would 
seem to be a serious objection to the statolith theory, but Némec (04, p. 58), on 
repeating Wiesner’s observations, finds, on the contrary, a confirmation of his own 
views. For movable starch-grains occur in the perianth of C. nobilis, but not in 
those of C. miniata. In the case of roots the distribution of the statoplasts is 
especially worthy of note. Physiologists have gradually come to believe that my 
father’? was right in his view that the organ of graviperception is in the tip of the 
root; and it is there—generally in the root-cap—and there only, that statoplasts 
are found. But these facts do not entirely harmonise with the statolith theory, 
as I shall show later on in the section devoted to experimental evidence. Here 
I will only add that the group of statocytes in the root are strongly suggestive 
of some special function, and those who deny that they form an organ of 
1 See Haberlandt (03) for a description of certain special cases of statocyte 
tissue, apparently replacing the endodermis. 
2 According to Haberlandt (03, p. 451), it is easy to be deceived in asserting that 
the endoderm contains no starch. Thus Fischer failed to find it in outgrown stems 
of some plants which possess it when young. Tondera (03) asserts that in certain 
Cucurbits the falling starch is only present in the older parts no longer capable of 
geotropism. But Miss Pertz, who has examined most of the species investigated by 
Tondera, finds statoplasts in the young parts where he failed to find these. 
Tondera makes some interesting remarks on the distribution of starch in the 
Cucurbits harmonising with Heine’s storehouse theory. It is obviously difficult in 
the case of the endoderm to distinguish between starch serving as a reserve and 
starch serving as part of the mechanism of perception. I see no reason why the 
second function should not be evolved from the first. 
3 Haberlandt (03, p. 461). 4 Darwin and Pertz (04). 
5 F, Darwin (99). 
® According to Némec they occur to some extent in the hypocotyl of Panicum. 
7 CO, Darwin (Power of Movement). 
