33° BOTANICAL GAZETTE [NOVEMBER 
2 show no arch and are essentially pegless. One is struck here 
by the small percentage of pegless seedlings in the culture in which 
the coats are removed, as compared with corresponding seedlings 
grown with the radicle pointing vertically downward. This is 
easily explained, however; the arching does not have to take 
place against gravity, due to the equalization of this stimulus by 
the clinostat. In short, the autonomic disposition to arch is unre- 
strained. This fact, with the fact that slight arching produces 
a one-sided peg in this form, makes the data exactly what must 
be expected. Again, one sees that the contact of the coats is 
much more effective in producing arching and one-sided peg- 
development than in the culture in which the seedlings developed 
with the radicle pointing vertically downward. This again must 
be expected, for the arching does not have to occur in opposition 
to gravity, since this stimulus is equalized by the clinostat. 
NOoLt states that more than 50 per cent of pumpkins grown on 
a horizontal clinostat show sharp arching, with the peg entirely 
on the concave side of the arch. This is the case if one allows two 
factors to act at once: contact of coats and the autonomic tendency | 
to arch. But Nott’s conclusion that such results will follow from 
the autonomic tendency to arch alone is erroneous, and was P0S- 
sible only because he overlooked the very important influence of 
contact of coats in the arching. Darwin’s statement that in 
seedlings of Cucurbita ovifera, grown on the clinostat, the peg 1S 
almost equal on all sides, certainly holds for the squash (Hubbard), 
providing both contact of coats and media are avoided, as they 
were in our clinostat cultures. 
From the experiments stated in this section several things are 
evident. Contact of coats is an extremely important stimulus 
for arch-production, both in the pumpkin and the squash. It 
produces strong arching even against gravity. In the pumpkin 
(Big Tom) any considerable arching increases greatly the percent- 
age of seedlings that show pegs; and it causes the development of 
the peg on the concave side of the arch. In the squash (Hubbar d) 
arching is far less effective in determining the lateral placement of 
the peg. The autonomic tendency to arch is very slight, though 
it tends to a lateral placement of the peg in the pumpkin (Big 
