PHYSIOLOGY. 954 
§ 251. 
it is an old observation, that each plant affects its 
peculiar soil, and that on this account, all seeds do 
not germinate in all kinds of soil, and at least soon 
decay in that which they dislike. Various, trials 
have been made, to make seeds germinate in various 
matters, different from the usual earths. Sukkow 
made sallad plants grow in pounded fluat of lime 
and barytes. Bonnet made plants grow in saw-dust, 
slips of paper, cotton, and even in. an old book. 
That cress, (Lepidium sativum), germinates upon a _ 
piece of woollen cloth is a well known fact. Mr - 
Humboldt’s experiments to make seeds germinate 
in metallic oxyds, especially the red oxyd of lead, in 
‘itharge, massicot, &c. aremore instructive. In powder 
of coal and sulphur, seeds germinated hkewise very 
well. , He found that oxygen proved an extreme 
stimulus to plants, and that without it, they never 
can be brought to germinate. On, this account ger- 
mination went on quickly in metallic oxyds, espe- 
cially in minium. In oil, on the contrary,) car- 
bon, hydrogen, in the filings of lead, iron, and cop- 
per, as well as in powdered molybdene and in al- 
kalis, no one seed germinated. It soon occurred 
to him, that with oxygen as a stimulant he might 
forcibly make seeds germinate faster, and he actu- 
-ally found, that at the temperature of 20° Reaum. all 
seeds vegetated most. rapidly when steeped in oxy- 
muriatic acid. One instance only will suffice. The 
seeds of the Lepidium sativum germinated after 6 
or 7 hours, when put into oxy-muriatic acid; where- 
R As 
