}, is found in black peppers. Its constitution
is represented by the following formula, the group which is united to the
piperidine ring, in this case, being piperic acid:

H_{2}
|
C
/ \
H_{2}C CH_{2}
| | /\ --O
H_{2}C CH_{2} | | \
\ / | | CH_{2}
N----OC.CH=CH.CH=CH--| | /
\/ --O

=Coniine=, C_{8}H_{17}N, is found in the umbelliferous plant, _Conium
maculatum_. Structurally, it is a propyl-piperidine, represented by the
following formula:

H_{2}
|
C
/ \
H_{2}C CH_{2}
| |
H_{2}C CH-C_{3}H_{7}
\ /
N
|
H

=Nicotine=, C_{10}H_{14}N_{2}, is the alkaloid of tobacco leaves. It is an
extremely poisonous, oily liquid, with a strong odor and a burning taste.
Its structural formula shows it to contain both a pyrridine ring and a
pyrrolidine ring, linked together thus

H
|
C H_{2}C---CH_{2}
/ \\ | |
HC C------HC CH_{2}
| | \ /
HC CH N
\ // |
N CH_{3}

=Hygrine=, C_{7}H_{13}NO, from coca leaves, is an acetic acid salt of
pyrrolidine, represented by the following formula:

H_{2}C---CH--OC.CH_{3}
| |
H_{2}C CH_{2}
\ /
N
|
CH_{3}

=Atropine= and =hyoscyamine=, C_{17}H_{23}NO_{3}, are optical isomers.
Atropine is an extremely poisonous, white crystalline compound, which is
obtained from deadly nightshade and henbane, and used in medicine, in
minute doses, a