44 6 L E T T E R S. 
in veffels from the continent of Syria, having Iain 
concealed during the voyage ? But how then came 
rhey to Roflagia,as you were pleafed tolhew me be- 
fore my departure from Upfala ? Could it be done 
in any other manner but by Chips from Dantzick, 
or fome place adjacent, where they infefted the' 
country that fummer ? Would it not therefore be 
proper, that all mailers of Chips fhould be obliged 
to take care, left they bring over fuch a deftrudtive 
vermin ? This ought to be done in the fame ftrift 
manner, as is now praflifed to prevent the plague 
from fpreading. 
(3.) I know of no one Europe who has made 
fufficient obfervations, relating to the migration of 
locufts : of the place from whence they firft fet 
out, and of the courfe they take. I have had an 
opportunity of making the following in Afia and 
Africa. 
The locufts, according to all appearance, feem 
to be directed by the fame natural inftindt as the 
Alpine rat ( Mus Lemmus, Lin.) in a diredl me- 
ridian line, by keeping nearly from Couth to 
north, as the other does from north to fouth, 
turning very little either to the eall or weft ; they 
come from the defarts of Arabia, take their courfe 
over thro’’ Palreftine, Syria, Carmania, Natolia, go 
fometimes through Bythinia by Conftantinople, 
and continue their journey through Poland, &c. 
as has happened in thefe latter years. They never 
turn from their courfe, for example, to the weft, 
wherefore Egypt is not vifited by them, though 
fo near their uiual track. The locufts therefore, 
are not to be reckoned amongft this country’s 
plagues in our times, as they were when Moles 
lived there, tho’ frogs, lice, cock-roaches, gnats, 
and all the vermin, which are mentioned amongft 
the 
