[ 5°8 ] 
The fubjedt of the fomnus' plant arum cannot but 
be highly entertaining to the lovers of natural know- 
lege: and fuch, I apprehend, cannot be lefs enter- 
tained with that faculty, which Linnsus calls vigihce 
Jlorum j of which we fhall give a brief account. 
Previous to our explanation of this affair it is pro- 
per to obferve, that the flowers of mod plants, after 
they are once opened, continue fo night and day, 
until they drop off, or die away. Several others, 
which fhut in the night-time, open in the morning 
either fooner or later, according to their refpedtive 
fituation in the fun or fhade, or as they are influenced 
by the manifefl changes of the atmofphere. There 
are however another clafs of flowers, which make 
the fubjedt of thefe obfervations, which obferve a 
more conffant and uniform law in this particular. 
Thefe open and fhut duly and conflantly at certain 
and determinate hours, exclufive of any manifefl; 
changes in the atmofphere j and this with fo little 
variation in point of time, as to render the pheno- 
menon well worth the obfeivation of all, whofe tafle 
leads them this way. 
This faculty in the flowers of plants is not alto- 
gether a new difeovery ; but we are indebted to the 
fame hand for additional obfervations upon this head 
likewife. It is fo manifefl in one of our common 
Englifh plants, the Tragopogon luteum , that our coun- 
try people long flnee called it Jobn-gc-to-bed-at-noon. 
Linnaeus’s obfervations have extended to near fifty 
fpecies, which are fubjedl to this law. What we 
find principally upon this fubjedt is in the Pbilofopbia 
Botanlca , p. 273. We will enumerate thefe plants, 
and mention the time when the flowers open and 
fhut, 
