FARMERS' REGISTER. 



[No. 6 



novices, he can find no where truths established by ex- 

 perience, or opinions (true or fiilse) venerable from 

 age. He is thrown upon his own resources, and com- 

 pelled to exercise his own reason and inventive genius. 

 The consequence is, that among many errors and loss- 

 es, some new and useful truths are sure to be discover- 

 ed—and these are speedily and extensively made 

 known, by the universal prevailing desire to seek and 

 profit by instruction on the subject. Hence it is, that 

 new as silk culture is in this country, improvements 

 have already been made, and questionable points have 

 been brought into discussion, which had scarcely been 

 thought of in Europe or Asia, where this business has 

 been pursued, and to great extent, for centuries. 

 Among these debated points, is the possibility of pro- 

 fitably rearing more than one crop of cocoons in a 

 season. The affirmative has been maintained in this 

 country — but not upon sufficient ground of facts and 

 experience to command general assent. 



But though in Europe, this question had before 

 scarcely attracted any notice, it is from that quarter 

 that we are now presented with valuable and con- 

 vincing experiments, made as their projector and con- 

 ductor evidently supposes, as to a subject entirely new. 

 The importance which M. Loiseleur-Deslongchamps 

 attaches to his discovery, is evinced in the title to his 

 communication, (published in the Annales de VJ-gri- 

 culture Francaise, for July, 1836,) which reads thus: 

 "New considerations upon the means of doubling, in 

 France, the crops of silk, by making, each year, many 

 rearings of silkworms," &c. His experiments were 

 accurately conducted, and are clearly detailed ; and 

 they will serve to throw much light on, if not to re- 

 move all doubt from the subject. Passing over his 

 more general and introductory observations, we pro- 

 ceed to translate what is material and useful. After 

 stating the great amount of raw silk annually imported 

 into France, and the necessity of supplying her manu- 

 factures from her own products, he proceeds thus ; 



" From the moment that I knew of the enormous 

 quantity of raw silk that our manufacturers purchased 

 from foreign countries, I had the idea that we might 

 double the product of the material, in France, if, in- 

 stead of a single crop of cocoons, it was possible to 

 have many. JBut I souglit in vain then, in the authors 

 within my reach, what they had said upon this subject, 

 I found nothing positive {de bien jwsitif) in Boissier 

 de Sauvages, in Dandolo, in M. Bonafous, and others, 

 that I consulted. Sauvages indeed had made some at- 

 tempts to preserve the eggs of silkworms beyond the 

 ordinary time, by heaping a certain quantity together, 

 and covering them with gum : but the trial had no suc- 

 cess. Without explaining how multiplied hatchings 

 were made in India, Dandolo and the author of the ar- 

 ticle "Vera soic" in the Nouvcaa Cours complct d'Jlg- 

 ricidlurc, say that in certain parts of that country, 12 

 crops of silk are made every year; but neither of them 

 indicate in any manner the process necessary to pro- 

 cure this product. It was necessary th(>n to seek how 

 to arrive at it: besides, the dilFerence of climate is so 

 great, that there was no probability that what was 

 practised in India, would be applicable to France. 



"The first trial which I made to procure a second 

 generation of worms was, by hatching a small packet 

 of eggs laid during the same season, in July, 1823. 

 Though kept exposed to the heat of the human body, 

 from August 1, to the end of Se[)tmeber, none were 



hatched : there came out not a single living worm — 

 and after the two months of incubation, all the eggs 

 were shrivelled and dried. It was necessary to have 

 recourse to other means." 



Thence supposing that exposure to the mild tempe- 

 rature of spring was necessary, after the cold of win- 

 ter, M. Deslongchamp was led to beheve — 



" that if the eggs of the silkworm could bear, with- 

 out injury, the temperature of an ice-house, it would 

 be the sure and easy means of carrying on, every year, 

 several successive rearings, and consequently of aug- 

 menting considerably the usual product of silk. In 

 consequence, in the first days of March, 1834, 1 placed 

 in the upper part of an ice-house, at the temperature 

 of zero,* or at most, at but a degree higher, many lit- 

 tle glass vessels, containing silkworm's eggs. My de- 

 sign was to withdraw them successively in the course 

 of the spring and summer, so as to make hatchings 

 and raisings that would succeed each other without in- 

 terruption. In order to preserve my eggs from the 

 great humidity wb.ich always prevails in ice-houses, I 

 had the vials well stopped, and carefully sealed with 



wax On the following 3d of July, I withdrew 



one vial from the ice-house ; and for fear lest too ab- 

 rupt a transition from a temperature of one degree 

 above freezing, to 17 or 18, (which was then the tem- 

 perature of the open air at mid-day,) should occasion 

 some damage to the eggs, I took "them from the ice- 

 house very early in the morning. Half an hour after, 

 I placed the vial containing them in a cellar, where 

 they remained for twenty-four hours : and at the end 

 of that time, it was removed to the coldest part of my 

 apartment. In short, I exposed the eggs to increased 

 heat as gradually as possible, to the time when placed 

 for incubation — which lasted 8 daj's, and by which, 

 the hatching was obtained on July 17. I kept all the 

 worms that left the eggs on that and the next day, and 

 of them made a raising (education) which lasted a lit- 

 tle more than 3G days, and from which I took awa)^ a 

 suitable number of cocoons for a purpose of which I 

 shall speak hereafter." 



In the same manner, and with like precautions, a 

 second hatching was produced on August 4th. Previ- 

 ously, experiments had been made by keeping the 

 eggs altogether in a cellar : but the variation of tem- 

 perature (from 6° to 9^°) was too great, to keep the 

 living principle dormant, and thereby preserve it ibr 

 future action. 



"It will sufllce to say, that in 1324, I made, suc- 

 cessfull}', five complete raisings of silkworms, at the 

 following times. 



" The first was the natural raising— ^hat is to say, it 

 was commenced May 10, witii worms hatched some 

 days after the opening of the leaves of the mulberry. 

 The cocoons which it yielded, weighed, on an average, 

 34 grains each, and 220 made a pound. f 



" The second raising, retarded by means of a tem- 

 perature of 6°, (above freezing,) commenced May 29 

 to 30. The cocoons obtained, were weighed too late 

 to estimate justly their true weight. 



" In the third, again retarded by the same means, 

 my worms were hatched June 20; and they made, 

 from the thirty-fourth to the thirty-ninth day, cocoons 

 of which 2:50 made a pound. The lightest of them 

 weighed 30 grains, and the heaviest 53 grains. 



* The Tliermoniotcr rnfurrod to in tliis piooe, is the Centi- 

 graflo, acc-oiiliMg to tlie scale or which Zero (0^) is the freezing, 

 and 100'-' the boiling point. — Kd. Fau. Ui:g. 



f The French pound is heavier than ours by one tenth — 92.64 

 of the former being equal to 100 lbs avoirdupoi3.^ED. Far. Reg. 



