young’
6o 5 ‘
fort of worms, if by frofts in the fpring they be loft for want of food ; this new fort isin referve to apply the leaves to profit once in the year. Theoretically the plan is good ;but there mull have been fomething in practice againlt it, or we may conjecture that aftermanv years the ufe of them would have been generally introduced.
This will not be an improper place to introduce fome remarks on this fubjeft, by anauthor tr. ch efteemed, but quite unknown in England. It appears from the work ofCount Carlo Bettoni, of Brefcia, that the difcovery of the new filk worm arofe fromexpeiiments made with a view of finding out a cure for the ficknefs of mulberry-trees,called moria ; this was fuppofed to arife from dripping the leaves in the fpring annually;it was thought that if fome means could be difcovered of podponing the gathering muchlater in the year, it would greatly favour the vegetation and health of the trees; an effectthat could only take place by means of a w'orm that would hatch much later than thecommon one In 1765, a fecond hatching of the eggs of the common worm is faid, bythe fame author, to have been made; part of which were fed with the fecond growth ofleaves, and part with the leaves of trees that had not been gathered in the fpring. Thofefed with the old leaves gave a greater number of cocoons, and of a better quality thanthe others. Thele experiments were repeated by many perfons ; and it was found, thatin the heats of July and Augud the w'orms would not do well; but in September muchbetter, and that the trees did not fuffer from having their leaves gathered in September,The fame author fays that the new worms (which he calls forejiieri) will hatch threetimes a year, and that no art will prevent it; no cellars, no cold will keep them fromit, though it may retard them lome time, as he tried in an ice-houfe, by which means hekept them inert till Auguft. But, on the contrary, the common fort cannot in generalbe hatched a fecond time the fame year, even with any heat that can be given ; yet headmits, that they were hatched by certain perfons in 1765. The new ones fleep fourtimes, like the common ones, but begin to fpin their cocoons five or fix days fooner ithey eat lefs in quantity, but give lefs filk ; and as this defedt is balanced by the advan-tage in food, they ought not, fays the Count, to be profcribed. Their cocoons are fmall,but the confiftency is good and fine; and their filk is fine and fofter than the common 1he lold it for 4 livres or 5 livres a pound more than common filk. There is, however,an evil attends them, which is the uncertainty of their hatching the fecond and third,time ; fometimes all the feed wall hatch, but at others only a part; even only the fe-venth and tenth of the quantity : but the fir!t hatching is regular, like that of the com-mon worms. A cireumftance in the courfe of his trials deferves noting, that he foundthe worms of both the old and new forts would drink water when offered to them,' andthat the cocoons were the larger for their having had the water.
They have had a fort in Tufcany that hatches twice a year ; and the Count writingthither for information concerning them, found that their filk was coarfer than the com-mon, and of lefs value ; and he judges them to be a different kind from his own, whichhatches three times. The Count concludes nothing determinate concerning them; butrefolves to continue his numerous experiments and obfervations. As there may be per-fons who think, as I did at firft, when I heard of this fort of worm, that if any fucceefi inEngland it would probably be this; it is proper to obferve that Count Betloni hadnothing in view but the difeafes of the mulberry trees, and does not feem to have had atall in contemplation the evils attending late frofts, depriving the worms of their ufualfood ; and if the common fort may be retarded in hatching (which lie {hews) till Auguft,equally with the new fort, there does not feem to be any extraordinary advantage in thisfort, for a northerly climate, more than in the others. The Count’s book * was printedat Venice in 1778.
* Progelto perprefervare i Gdft, & c. Co. Carlo Bettoni. 8vo. Various paffages.
Sig*