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till it comes within their reach. They no sooner perceive the fresh food than they abandon the rubbish below, and creep through the meshes, so as to fix themselves upon the leaves; then by gently raising the fresh basket, and drawing out the board below, (which ought to be made to slip out, like the slip bottom of a bird's cage,) you get off all the excrements and decayed leaves, without incommoding the worms in the smallest degree; and along with the litter you will draw off an inch or two in depth of the foulest mephitic vapours. To get entirely rid of these, the board, when thus taken out, fhould be carried without doors, and there cleaned; and the slip board immedi ately replaced to receive all the excrements and offals.. After it is replaced, the wire frame that had been elevated a little, may be allowed to descend to a convenient distance above the board, without touching it. Thus, will there be left a vacant space for the mephitic air to fall below the worms, so as to allow them to, inhabit a wholesome region of the atmosphere.

*

When a fresh supply of food is to be given, before cleaning, the wire frame ought to be let down as close to the board as can be safely done, and another wire bottomed frame put over it, with fresh leaves, as before described. When the worms have abandoned that in their turn, let the slip board, together with the lower wire frame, be drawn out and removed; and so on. as often as necessary. To admit of this alternate change, every table, consisting of one slip board, ought to have two sets of wire-bottomed frames of the same size; the slip board to be always put into its place immediately after it is cleaned, and the wire

(

frames reserved to be afterwards placed over the other.

By this mode of management it is probable that the worms would be saved from the diseases engendered by the mephitic air; and the numerous deaths that are the consequence of it avoided.

But still farther to insure this salutary effect, another measure, recommended by some philosophers, might be conjoined with it. Every one now knows that quicklime absorbs fixed air with great rapidity. From this known property of quicklime Mr Blancard, a gentleman in France, by way of experiment, went even so far as to strew quicklime upon the worms themselves. This harsh procefs, he found not only did not kill the worms, but they continued in health, and more vigorous than before, and yielded larger cocoons than others which had not been so treated. Instead of this mode of applying quicklime, however, I should advise rather to strew a thin stratum of fresh slaked quicklime upon the slip board, each time it was cleaned, immediately before it was put into its place. This would absorb the mephitic gas as it was generated, and descended upon the surface of the quicklime. Thus would the worms be kept continually in an atmosphere of pure airt. Were the walls of the apartment to be frequently

J

* Memoires par la societé royale d'àgriculture, de Paris; trimestre de prin tems, 1789.

+ To put this question beyond a doubt, Mr Blancard made the fol lowing comparative experiments, which were several times repeated. "I procured," says he," four glass jars, nine inches high, and five in diameter, closing the mouth with cork stoppers. After which I placed in each of them, in their second life, (so I translate mue, which means the stage between the different sicknesses,) twelve silk worms, which were fed four times a-day; and which I confined in this kind of prison all

washed with quicklime and water, it would tend much to promote cleanliness at a small expence, and augment the healthinefs of the worms, as well as that of the persons who attend them.

The circumstance of the silk worm never sleeping during the night, is a new particular respecting the natural history of this animal, the notice of which we owe to mifs Rhodes, and which I suppose is perfect, ly well founded. From this very circumstance, however, it would seem that nature had intended that light or darkness fhould make little difference to this singular animal. My fair correspondent has, I fhould suppose, committed a small mistake when she supposes the silk worm is a native of polar regions, where only, there is no night at one season of the year; for though some parts of China, which seems on all hands to be allowed to be the native place of the silk worm, approach to the polar circle, yet, as the greatest part of that country extends towards; the tropical regions, where the day and night are nearly of an equal length, we may rather believe it. was there, where the mulberry thrives best, that the silk worm was first produced. But this is a matter merely speculative; for we know that nature may their life, without taking away either their dead companions, or their ordure or litter. I sprinkled with chalk the worms of only two of these jars, and kept the two others to compare with them.

"In those without lime, I never obtained neither more nor less than three small and imperfect cocoons, (chiques ou bouffard,) and in the two that were sprinkled with lime, I had very often twelve, and never lefs than nine fine full sized firm cocoons."

This experiment affords the most satisfactory proof of the utility of this process. From a number of trials he found, that even when the worms were covered with a very large proportion of lime, they neves were in any way incommoded by it.

be in many cases helped by art, and even in some cases improved by adopting practites directly contrary to it. If bees were left without hives, which nature provides for them only in a very imperfect manner, the whole race of them in Europe would quickly be exterminated; and though cattle were doubtlefs intended by nature to run abroad in the open air, and calves to enjoy the benefit of light; yet it is well known that neither of them fatten so well in these circumstances, as if they be confined in total darkness, and there fed abundantly.

The mortality among the worms, during this wett season, is exactly what might have been expected, Had the lettuce, however, been kept under a moveable cover from rain for a day or two before using, especially if open to the sun at the same time,. which, in a proper exposure, may be in some measure effected, this evil would have been obviated. Since the receipt of mifs Rhodes's letter, I have been favoured with the following communication from another lady, who is exceedingly accurate in her observations, and who is, from motives of philanthropy, extremely anxious to forward this undertaking. It tends to show that by great attention it might be possible, in some cases, to obtain even fresh dry mulberry leaves during a rainy season, were the superintendants of silk works extremely attentive; though on a large scale, where many persons are employed, this would be a matter of considerable difficulty.

"Mifs

had got a dozen mulberry plants last year, but not being sufficiently advanced to be of much use, he sent to for her general

supply. To save trouble, and for experiment, she had fhoots brought her, 8, 10, or 12 inches long; the leaves on the under part were stripped off, and the ends of the shoots put into water-the water renewed daily. By this means the leaves on the upper parts of the fhoots were kept in perfect good order, and though sufficiently, or indeed perfectly fresh, could never be wet. The few worms fhe had, were supplied twice a day with these leaves, some of them attained the size of 34 inches, others 3 inches, none below 2 inches. One had 420 eggs, another above 300, and none below 270, which shows the leaves were in good condition.

"The worm arrived at as large a size as Mr Andrew Wright's at Paisley, from whom the eggs came; and the average number expected from each female, that gentlemen writes, is, 250.

"Mr Millar writes in his dictionary, or elsewhere, that it hurts the mulberry lefs to take off the shoots altogether, than to strip the fhoots of the leaves."

There can be no doubt but by this practice, if a bason were provided, with a proper apparatus for receiving the shoots, and exposed to the sun or wind, under a roof, it might be possible to find dry leaves even during rainy weather, though at a considerable expence, where the quantity of worms is great. Perhaps the best way to have very fine leaves, and healthy plants of mulberries, is to have them cut close to the ground every winter, as we at present do with oziers for baskets.

I am much obliged to mifs Rhodes for the cocoons of the black worm the was so obliging as to send.