4 
other plants. Every few years the drug trade is 
exercised over substitutes offered more or iets honestly 
y ors and jobbers. It is only a short time 
since cascara sagrada, the bark of Rhamnus Purshiana, 
was replaced very considerably by the bark of a related 
species, Rhamnus Californica, the latter of much 
inferior quality. It is also only a few years since the 
trade journals contained an extensive description of 
the substitution of the roots of Polygala alba for the 
senega snakeroot, 5 ly ae Senega. Not many years 
o, a sample of tans ich was submitted by a 
large wholesale fess proved, probably as the result 
of a clerical blunder, to be pansy. 
The direct solution of oreblens of identity like the 
rasadltne | is “da closest link between hay any and phar- 
macy, the most obvious medical bota Itisa ee 
of the study of vegetable pharmacognosy. The las 
instance mentioned is a very simple one. The me fest 
tyro could detect the mistake and guess pretty closely 
at the cause for it; but in the other casesa discrimina- 
tion between the things to be compared proved decid- 
oe more difficult, 
s they come to the wholesaler and the manufac- 
fruit and seed rarely, as in the case of opiu 
are the active eaucinke collected to any eet ex tate 
freed from t f the plant which produce 
em. Hence, in the great ENS of cases, the 
medical botaniet § em expected to oe name cer- 
tain parts of fairly well-known plan 
It has, unfortunately for this ison been the habit 
of descriptive botanists to aim at as brief a diagnosis of 
each species as possible, and to use those characters 
which most surely and most readily serve to separate it 
from its congeners; orelse, as is the case with much mod- 
ern work, what are felt to be the less aici and con- 
sequently the surest and most permanent ecseaays 
have been taken as the ‘aie of classification of 
the more obvious features being left satiealy ae 
