359 PRINCIPLES OF BOTANY, ETC, 
shape, (§ 245). Even though the seed should be 
mnverted and put into the ground, so as to turn the 
rostel towards the surface of the ground, yet it never 
will grow upwards. It grows long, but soon turns to- 
wards the ground, and then the seed recovers its pro- 
per position. ‘This observation, which we ean make . 
every day, especially in the kidney bean, (Phaseolus 
vulgaris); in the common bean, (Vicia faba), and 
other culinary seeds, has greatly attracted the atten- 
tion of botanists. Dr Percival compares it to instinct 
in animals, and endeavours to prove by it, that plants 
have sensation and consciousness. Dr Hedwig ac- 
counts for this tendency of the rostel downwards in 
a twofold manner: In the first place, the sap is, by 
the two chyliferous ducts accumulated in the extre- 
imity of the rostel, which therefore becomes heavier, 
and of course, according to the laws of gravity, is 
drawn downwards. In the second place, the meis- 
ture in the extremity of the rostel, is attracted by 
that of the ground. But both these reasons appear 
to me to be insufficient to explain this phenomenon 5 
forfirst, the power of gravity and attraction is one 
and the same power; and secondly, the cotyledons 
contain by far more moisture, and they possess a 
ereater absolute gravity ; but notwithstanding this are 
often by the rostel pushed above ground. We are 
in fact as little capable of accounting for this pheno- 
‘menon, as ‘to give reasons why some caterpillars spin 
a case, while others bury themselves in the ground. 
We are ignorant of the nature of this as of many other 
‘operations in organized bodies. ‘The only reason 
which can be brought forward to hide our ignorance 
iS, 
