C 236 ] 
manna already mentioned undergo no kind of 
preparation whatfoever, before they are exported ; 
fometimes they are finer, particularly the manna 
grajfa , and fometimes very dirty and full of impuri- 
ties ; but the Neapolitans have nointereft in adulterat- 
ing the manna, becaufe they always have a great deal 
more than what they generally export > and 
if manna is kept in the magazines, it receives often 
very great hurt by the Southern winds, fo common in 
our part of the world. The changes of the weather 
produce a fudden alteration in the time that the 
manna is to be gathered ; and, for this reafon, when 
the fummer is rainy, the manna is always very fcarca 
and very bad. 
With regard to the ufe we make of manna in the 
practice of phyfic, I believe it is of very little con- 
fequence ; for it cannot be employed alone as a ca- 
thartic, becaufe you muft give a confiderable dofe in 
order to obtain a tolerable operation ; it is commonly 
prefcribed for children, who fooner take it becaufe it 
is fweet, and fometimes is given in colds and coughs : 
the generality of the phyficians at Naples often 
give manna and falts to keep the body open in the 
beginning of many fevers, in which there is a foul- 
nefs of the primes •vice. We do not give any pre- 
ference to the manna, in any particular cafe, and 
rather confider it as an article of trade than a very 
ufeful medicine. 
After this fhort account of the manna, according 
to my promife, I fhall give you a little of die hiftory 
of the Tarantula, becaufe I have had an oppor- 
tunity of examining the effects of this animal, in 
the province of Taranto, where it is found in great 
abundance : 
