426 Vines . — On Epinasty and Hyponasty . 
rose up from the horizontal position, the youngest ones be- 
coming erect. At the same time the rising leaves became 
strongly involute, the lateral margins of the lamina being 
curved inwards towards the upper surface of the midrib. The 
older leaves showed marked epinasty. 
A similar plant was, at the same time, rotated on the clino- 
stat in darkness for seventy-two hours. The leaves of this 
plant behaved in precisely the same manner as those of the 
plant in the normal position. 
The leaves of a plant which have risen in consequence of 
having been kept in darkness, return to the horizontal position 
in two or three days when exposed to light. 
Taraxacum Dens-Leonis. The leaves of this plant behave 
in a quite similar manner to those of Plantago , except that the 
transverse hyponasty is less marked. 
The change of position of the young radical leaves of these 
plants in the normal position in darkness was described by 
Frank, and was attributed by him to negative geotropism, — 
an explanation which seems to have been hitherto accepted 
without question. The clinostat-experiments, however, prove 
that this explanation is not in accordance with fact. The 
movements can only be due to hyponasty, both longitudinal 
and transverse. These leaves present the peculiarity that the 
change from the hyponastic to the epinastic phase of growth 
takes place at a relatively late stage in their development. 
Remembering Batalin’s observation, to which reference was 
made above, that certain growing leaves rise at night, such as 
those of Chenopodium , Cabbage, Polygonum aviculare , Stellar ia, 
Linum , etc., I made some observations on two of the plants 
mentioned by him, namely P. avicidare and Linum usitatissi- 
mum. I found that, when placed in darkness for twenty-four 
hours, in the normal position, the previously horizontal younger 
leaves of these plants rose up hyponastically, becoming erect, 
and that the same effect followed in darkness when the plant 
was rotated on the clinostat. 
A more important observation was made with M archantia. 
A plant growing in a pot was placed in the normal position 
