(= “PERAK MUSEUM NO res / NO. ea f f / ON THE PXPEREMENTAL CUERITURE SILKWORMS IN PERAK, TOGETHER WITH A PAPER ON THE MALAYAN FISH POISON “ AKER TUBA,” AND A NOTE ON A. LIGHTNING DISCHARGE IN TAIPING. ALSO A NOTE ON THE BLACK LIMESFONE AT KAMUNING. BY BeaVRAYayEN., M.I.E.E., F.Z.S., COR. MEM. P.S., ETS. Taiping : PERAK GOVERNMENT PRINTING OFFICE. 1893. Price.35. Cents, ee Dera Wuseum Mofes/ Mo. L. ON THES EXE ERIMENTAL GUL TURE OR SILKWORMS IN PERAK, ETC ON bE Jee edie IN re bea CO ON Ra SEI W OIMES, CENe Pe Eanes TOGETHER WITH A PAPER ON THE MALAYAN FISH POISON ‘““ AKER TUBA,’ AND A NOTE ON A LIGHTNING DISCHARGE IN TAIPING. ALSO A NOTE ON THE BLACK LIMESTONE AT KAMUNING. BY Ee WIRY: WINE, =”. ANA _—s M.I.E.E., F.Z.S., COR. MEM. P.S., ETC. fix?) Vis iY ( ( JUL B85 208° Os 12Qq SP Os 2 \ 7/> d3 Taiping : PERAK GOVERNMENT PRINTING OFFICE. 1893. NOTICE. From time to time, as material is available, it is proposed to publish, in pamphlet form, parts of a serial under the title of Perak Museum Notes. The papers in it will deal with and illustrate Museum and general scientific subjects connected with the State of Perak, its history, trade, industries, mines and products, Communications and papers on the subjects indicated above are invited. ON THE EXPERIMENTAL CULTURE OF STLK WORMS IN PERAK. In November, 1889, a small Chinese company, after having cleared and planted up a few acres of land with mulberries at Ayer Kuning, in Larut, introduced from near Canton, in China, some silkworm eges. These eggs hatched, and successive broods of the worms were raised and seemed to thrive in a perfectly satisfactory manner. Mr. F. Light then planted up some land at Ayer Kuning with the same ‘mulberries, and began breeding the worms from eges given him by the original Chinese company. CHINESE METHOD OF CULTURE. The eggs are laid on sheets of common yellow Chinese paper, known in the shops as kertas api. When the time arrives for the eges to hatch, the sheets of paper are laid on bamboo trays and lightly sprinkled with finely cut mulberry leaves, and the worms aus they emerge from the eggs crawl on to the cut leaf and are removed with it to fresh trays. These trays are round, and are made of split plaited bamboo; they are from two to three and av half feet in diameter, and have a rim of about one and a half inches high. The worms are kept on these trays, at first on a few; as they grow and require more room, the number of trays is increased. The trays are put on rough round wood racks, about nine inches apart. Cut leaf is given for the first five or six days and then the worms, having grown large enouch, are fed on uncut leaf. The trays are kept clean, the refuse leaves, dead and sickly worms, ete., being removed daily. The houses, which are of the ordinary high- -pitched attap roofed Chinese pattern, are kept as much ‘shut up as possible, to exclude the wind and sun. ‘The west wind is thought to cause sickness amongst the worms. Lights are kept burning at night, and the houses are used as dwellings by the cultivators. Smoking, by the bye, is not allowed as it is thought to be prejudicial to the welfare of 2, CULTURE OF SILKWORMS. the worms. When they are full grown, and as they turn yellow, they are picked out of the trays and put on to the cocooning frames to spin. These are bamboo frames with thin strips of eurled bamboo fastened to them on each side, and it 1s in the loops so formed that the worms spin. The frames are about two feet by three feet, and are stood up in pairs in the houses when required for use. The spinning completed, the cocoons are picked out of the frames by men armed with small steel forceps. The earliest of the spinners are reserved for breeding and the remainder are stifled. The cocoons kept for breeding are put in a single layer on the bamboo rearimg trays. When the moths emerge they are allowed to pair, and in the evening the pairs are separ rated, ie females being placed on a sheet of common Chinese paper on which a wooden frame is placed a little smaller than the size of a sheet of paper. These frames are about one anda half inches high. A board is laid on top of the first frame, then a sheet of paper, then another frame, which, having been filled with female moths, is covered with another board, and so on. As soon as the moths have laid they are thrown away, and the sheets of paper, densely covered with eggs, are dipped into hot water, the water being heated so that the hand can te borne in it. The sheets are then dried, the date of laying marked on each sheet, and they are rolled up and put away until they are ready for hatching. The dipping in hot water is a matter requiring great care, as if the water is overheated it kills the eggs. It is said to make the eges hatch more evenly and is thought to be of great importance by the Chinese.* TREATMENT OF THE SILK. The cocoons not required for breeding are put into wooden drawers with perforated bottoms, arranged in a large chest, be- neath which are put earthenware chafing-dishes, in which char- coal is burned. ‘This kills the chr ysalids : and in a few days dries them up. Care must be taken, or the silk gets scorched, if the heat is too great. Another method of stifling used by the Chinese is to take the cocooning frames full of cocoons and heap them wp and then cover them all closely over with cloths. The chafing- dishes with burning charcoal are then put underneath the pile and the stifling ensues, *T have found that if the eggs laid by a pebrinous moth are washed, and the water examined under the microscope, the corpuscles of pebrine will be found in it; showine that these corpuscles were in the fluid used by the moth to stick the eges on with, and it is conceivable that a moth which had become diseased late in life, and after the eges were formed, might lay pure eggs, but that some of the young worms in eating their way through the shell of the eges might contract the disease by eating the corpuscles on the exterior surface of the eggs. Can this have anything to do with the Chinese hot water process ? CULTURE OF SILKWORMS. 3 When killed and dried the cocoons are sorted into yellows and whites, or as the Chinese express it, gold and silver, all damaged cocoons being put by Hemisclvces together with the pierced cocoons which have been used for breeding purposes. The cocoons are sent to Hongkong and from there to Hang- kau, where they are sold. A man being sent with each consign- ment of silk, the transport expenses are very considerable. “In China the silk is reeled and sent back again past Penang to Kurope. The price of well reeled silk in China is 55 per iat while badly reeled silk only fetches $3. An attempt was made to introduce some female reelers from China, but without success, owing to the difficulty of getting them out of the country. There is one woman in Larut who can reel, but she left China when very young and is therefore not an expert hand. The apparatus used in reeling is very simple, and only costs from $3 to $5. In some observations that I made on the yeild of silk I found that the average weight of the cocoons when fresh was 10°75 grains, 651 going to the pound. I estimated that 5,853 cocoons would yeild one pound of reeled silk, besides the floss silk. Mr. F. Light sent samples of the Ayer Kuning cocoons to Messrs. C. S. Tennent & Co., of Penang, who obtained the follow- ing interesting report on them from their correspondents at Marseilles. “We thank you for your cocoon samples marked Land D, which we have submitted to our broker. The cocoons you send are unpierced and are similar to what are received from 3engal, and very good samples of their kind. Our broker has never seen anything of exactly the same kind. You will notice that each cocoon has an outer envelope of tough silk, and this should be removed in Penang and shipped as silk waste: it is worth from | to 1.50 francs per kilo, landed terms (this is, about 173 to 26 cents per kati). To give an exact valuation it is however necessary to know what the silk contents of your cocoons are, that is, the weight of cocoons required to give one kilo of silk, and before this is known it is impossible to say what the cocoons would fetch, as spimners themselves are in complete uncertamty before making a spinning trial of the cocoons. Bengal and China unpierced cocoons are frequently sold with the guarantee that 4 kilos weight of cocoons at a certain temperature shall give one kilo weight of silk, and if the 4 kilos weight of cocoons give, say, 1100 kilos silk, the buyer pays 10 per cent over contract price, and vice versa if the silk out-turn is less than one kilo. There is a Silk Trade Association here and at Lyons, by which the spinning trials are made, and the spinners’ names are unknown to 4, CULTURE OF SILKWORMS. either buyer or seller. Of course these are very complicated and delicate trials, and only people with a large experience in the article sell on these guarantee terms, though cocoons produced by silkworms from the same place, fed in the same manner and under the same climatic conditions, vary very little in the silk out-turns they yield. “The best way to get into the business is to ask Penang to send as soon as possible about 10 kilos (16; katis) of L, and the same quantity of D, removing the outer envelope, and with these we will have spinning trials made by the Association, and will then have a basis for future business, and know the exact value of the cocoons. We will then be able to sell on tale quale terms, without guarantee. “Your cocoons are known as unpierced spinning cocoons (cocons non percés « filer), and produce the so-called ‘satin silk’ (soie satinée). They might be worth about 5 to 6 frances per kilo, but until thetr silk yield is known, any valuation is very loose and variation lable.” THE VARIETY OF SILKWORM. As has been previously stated, the breed was introduced from near Canton. They appear to be the variety known as bombyz sinensis, which is a small multivoltine species, inferior to some of the Indian breeds. It appears to be not a true multi- voltine, as there is always a certain proportion of the eggs which refuse to hatch, and which assume the appearance of annual egos, and evidently require the cold of a winter before they will eerminate. Sometimes these annual eggs form a considerable percentage of the whole laying. It would appear that in China these worms lay multivoltine eggs during the summer, and in the autumn lay eggs which do not hatch until the following spring. A second importation of eggs was made from China, and I obtained a few and reared them for three generations, and then they died out in consequence of all the eggs being of the kind which require exposure to cold before they will hatch. Those evos which only slightly darken to a yellow are the quick-hatching oD egos, On the fifth or sixth day they turn to a pretty pale French erey, the heads of the worms then appear as black dots, and on the seventh day they hatch ont. The other eggs, on the con- trary, begin to darken soon after they are laid, and on the third or fourth day have become brown or purplish brown, and may then be kept for months without further change. The eves which were brought from China were all of this character. They reached here in November, so were the autumn laying. The life history of this worm will be seen by the following notes, made on some that I reared in 1890. From the laying of © CULTURE OF SILKWORMS. 5 the eggs to the hatching took between six and seven days, the egos being kept in a cool place. The first change of skin took place on the seventh day, the second on the tenth, the third on the fourteenth, and on the nineteenth day the worms attained maturity and began to spin.* The spinning took from two to three days, so that from the laying of the eggs to the completion of the cocoons takes about 50 days. It may “therefore be assumed that two broods could be reared in three months, or eight in the year. The silk varies in colour from pale greenish yellow to white. The Chinese, however, bred out the greenish and yellowish varieties, and the strain now in the country is almost pure white. CHINESE MULBERRY CULTURE. The mulberries were introduced from China, being brought here as cuttings. They are a big leaved, long fruited variety, and grow into bushes. The jungle was felled ad the land was then “stumped and dug over to remove roots, made into shallow ridges, and the cuttings planted on top of them at distances of about one foot apart along the rows, the rows being three feet apart. The land was all carefully drained by deep "ditches and kept free of weeds by constant hoeings, the plants being manured by the refuse leaves, etc., from the rearing of the worms. The plants being so close, it is not possible to allow them to grow to any size, and they are therefore kept down by periodical severe prunings. As might be expected, by forcing the plants to grow under these very artificial conditions, he least neglect or disease tells very seriously on them, particularly when ‘they are being continually stripped of their leaves to feed the worms. DISEASE OF THE MULBERRIES. In July of 1891 I went to Ayer Kuning and noticed tha all the mulberries were affected by a leaf disease much resem bling in its general appearance the well-known coffee leaf disease On the young leaves faint yellowish dots were to be seen, and these bécame larger and more yellow on the older leaves, and reached a diameter of about one-third of an inch. Beneath, these spots were more or less covered with bright yellow spores. The leaves dropped long before, in the natural course of events, they would have done, and the bushes looked very bare and miserable in consequence. Almost the entire plantation was affected, but the Chinese said that the worms would eat the diseased leaf, and I saw it being given to them, and they * In November and December the worms change their skin once more than here stated, and are about five days longer in attaining maturity. 6 CULTURE OF SILKWORMS. appeared to eat it the same as if it had been good leaf. The Chinese said that the worms were quite healthy and that deaths amongst them were very rare, but subsequent events showed that this information was incorrect. They admitted that m con- sequence of the disease they had been short of leaf, and had not been able to rear as many worms as they expected. A microscopical examination of sections of the leaf showed that the disease was caused by a fungus growing entirely with- in its substance. A spore evidently settles on the under-side of a leaf, throws out a thread which penetrates mto the first stomata it comes to, and then, finding nourishment, increases within the tissues of the leaf, which becomes yellow and con- siderably swollen at the centre of the spot. One or more of the stomata on this swelling become much enlarged internally, and filled with bright yellow spores, which eventually are forced by those beneath them out of the now expanded external orifice of the stomata. The spores are rather irregular in form, some being spheri- aaa inch in diameter, In water the transparent spore case becomes distended and separated from the granular yellow nucleus, which it then encloses, as the white of an egg does the yolk. When placed in a drop of water on a cover-glass, inverted over an open vasilined cell of a microscope slide, so that evaporation is prevented, the spores may be seen to swell as above stated and eventually to burst; the yellow contents then float out as separate eranules, which each begin to swell until they attain nearly the size of the original compound spore, and in about four hours the swollen eranules, which are spherical and are the true spores, begin to throw out slender, distantly jomted, waved threads, sometimes branched. Occasionally one or two of the yellow granules swell within a mother cell and germinate, and the mycehal thread or threads pierce the wall of the mother cell, which then has the appearance of being an actual spore; but I believe I am right in saying that it is not so in reality. I have not been able to con- tinuously watch for hours a particular cell under the microscope, as should be done in investigations of this sort, but have only been able to devote spare minutes at odd times to the work, therefore it is just possible that I have misinterpreted the method of germination. Itis nearly certain that the spores only germinate when in a drop of water, and attack the leaf only, when that drop happens to be on the under-side of a leaf. cal and others oval. They measure about The mulberry which has been planted at Ayer Kuning was introduced from China. The Chinese, however, say that they have no recollection of having seen the leaf disease on the CULTURE OF SILKWORMS. if mulberries in China, but perhaps the climate here may be particularly suited to the development of the fungus, while in China it is not, and the disease there may be sporadic, and do little or no damage. Mulberries were introduced into Perak from India at least eleven years ago, and I have examined a number of these trees and bave not seen a single spot of disease on any of them. This shows that the disease is not indigenous to Perak, but that it was brought along with the cuttings from China, and I raised the question whether the two small planta- tions which had been started at Ayer Kuning, and which were both badly affected by the disease, should not be destroyed before it spread further, or at least measures taken to disinfect them. Another question which suggested itself was, whether the mulberries which were introduced from India, and which are apparently both of different varieties to that recently introduced from China, are susceptible in the same degree to the ravages of the disease. To test this I gave young plants of both kinds of these Indian mulberries to the Chinese, and afterwards also to Mr. Light, requesting that they might be planted amongst the affected bushes. Some two months afterwards I examined these plants and found that they had contracted the disease equally with the Chinese mulberries amongst which they were planted, thus proving that they were not proof against the disease and that had the disease been indigenous to the country they would have caught it during the eleven years they have been here. INSECTS DESTRUCTIVE TO THE MULBERRY. So far, I have only noticed one insect which does any con- siderable amount of damage to the mulberry bushes. This is the common yellow and green diamond beetle. It damages them when in the imago state, by eating the leaves. At certain times of the year they are very abundant and do serious injury to orange, lime, lemon and pomeloe trees. RAMI AS A FOOD PLANT. A paragraph having gone the rounds of the newspapers to the effect that it had been found that rami (China grass-cloth plant) had been successfully used as a food for silkworms, and that they not only throve on it but that the yield of silk was largely increased, I tried the experiment, and found that not only the worms that had been fed on mulberry, but also the newly hatched ones, which had not previously been fed at all, absolutely refused to eat it, preferring death by starvation. I tried cut and also crushed leaves with the same result. There would therefore appear to be no doubt that rami cannot be used 2 8 CULTURE OF SILKWORMS. as a food plant for the variety of worms now in Perak, though the annual varieties may possibly be induced to eat it.* ENEMIES OF THE WORMS. I have noticed two species of spiders, the common reddish coloured house ant, and a wasp as offenders; the most destruc- tive being the ants, who on one occasion killed a tray of over fifty worms in an hour or two. None of the worms seemed to have been eaten, merely stung to death. Putting the tray stands in cups of water and enclosing the whole in netting would of course prevent loss from these insect pests. The house lizard, rats, and the magpie-robin have also to be cuarded against, as they will all devour the caterpillars when- ever they get the chance, and they are most persistent in their attempts. DISEASE OF THE WORMS. I was informed in August, 1891, that there had been con- siderable losses amongst the worms at Ayer Kuning, and on visiting the original Chinese cultivators I found that the whole of phere worms had died out, and they had not a single live one left on the place. Mr. Light stated ‘that after attaining a size of about three-quarters of an inch in length the worms went off their feed and ceased growing, and that it was the opinion of the Chinese that the worms were diseased. JI at first thought that the leaf disease might be the cause of the unhealthiness of the worms, as I failed by a microscopical examination of some of the young worms to detect any of the bacteria which cause the or silk-worm diseases. About ten days afterwards I again visited Ayer Kuning, and took some thirty of the weak worms, which had dropped off the cocooning frames, and which were * “ A discovery has been made by a lady in Columbia, §.C., that may have a marked effect upon two great industries. For a number of seasons this lady has amused herself by feeding silkworms and sending a few pounds of cocoons to the Women’s Society for the Encouragement of the Silk Industry in Philadelphia. The extraordinary warmth of this winter caused the eggs to hatch far in advance of the season, and as the young leaves of the mulberry and the Osage orange had not put forth, our amateur was at a loss what to do. An account adds :— “Seeing that the foliage of the ramie in a neighbouring field was putting out, she gathered some and put the worms upon it. They fed ravenously, and she kept up the supply until the Osage orange leaves ap- peared. Then she divided her worms equally, feeding one set with ramie, the other with Osage orange. She kept the cocoons separate and sent them to Philadelphia. The experts there were astonished at the size of those spun by the ramie eaters, and wrote to the lady to know what she had done to secure them. They were not only larger, but the silk was finer.’ ”’ —Kew Bulletin, No. 44 of 1890, pages 174-5 CULTURE OF SILKWORMS. 9 anable to spin properly, for examination, as these feeble indivi- duals are sure to show disease, if present at all in a brood. All those that I examined under the microscope were swarming with panhistophyton ovatum, of Lebert, the bacterium which causes pebrine, the worst disease to which silkworms are lable, as it is not only infectious but hereditary, This disease could have no sort of connection with the mulberry leaf disease, but must have been imported from China, either in the eggs or by means of infected trays or cocooning frames, which were all brought from China, or it may have been contracted in the way which will be mentioned hereafter, On previous visits that I paid to Ayer Kuning I had been assured by the Chinese that they had had no deaths amongst their worms, but financial reasons may account for their not. eiving correct information on this point. The micro-organism causing the disease is thus described by Mr. E. M. Crookshank in his Practical Bacteriology :—* Pan- histophyton ovatum, Lebert (nosema bom micrococcus ovatus, 3 corpuscles du ver @ soie), Shining oval cocci to —, mm. long, z 1, 000 1,000 000 2 25 Too MM. wide, singly and in pairs, or masses; or rods, Air) mm. thick and twice as long. They multiply by sub-division. They were experimentally proved to be the cause of pebrine, gattine, maladie des corpuscles, or flecksucht; and were discovered in the organs of diseased silkworms, as well as in the pupe, moths, and eggs.” I have not detected any of the three other principal silk- worm diseases—grasserie, muscardine and flaccidity—amongst the worms in Perak. FAILURE OF THE CULTIVATORS. After repeated losses caused by the death of whole broods of worms, and by the much reduced quality of the silk yielded by the silkworms, both the original Chinese cultivators and Mr. Light abandoned the attempt. of cultivating them in February of 1892, after having made a fresh importation of eges from China at the end of 1891. These, however, as they were reared in the same rooms and on the same trays as the old ones, naturally contracted the disease and also died out. EXPERIMENTAL BREEDING TO ELIMINATE THE DISEASE. On 10th September, 1891, I wrote as follows on this subject : “ Having proved the existence of pebrine amongst the worms here, it isa subject for the consideration of Government whether (a) they will take any measures to stamp it out, or (b) let the intro- duction of silk-growing in Perak become a failure, as it most surely will without Government intervention, 10 CULTURE OF SILKWORMS. “The measures to be taken are as follows :— (c). The destruction of all the worms now in the State. (d). The disinfection of the houses and apparatus used. (e). The introduction of fresh ‘“ seed,” free from disease. (7). The prohibition of the importation of other “ seed.” “It is probable that the easiest way of carrying out these measures would be to get “seed” from the Government breeding establishment in India, but that would entail the sending of some one to bring it over, as the attempt already made to send it by post has failed, for reasons previously stated. “A second way would be to get “seed” from China, and rear it under Pasteur’s system. * And a third way would be to select, by Pasteur’s method, a healthy strain from the worms now in the country.” The Government decided to procure seed from India, but im consequence of hearing that the silk-breeding experiments under- taken in India had not proved a success, and that the eges could not be guaranteed, this had to be abandoned, and in November I obtained permission to tr y the third course indicated above. Shortly stated, the Pasteur system, which has saved the silk industry of Europe from the utter ruin which threatened it, is the rejection, for breeding purposes, of the eggs of those moths which, on examination, are found to be diseased. This, in the case of the Ayer Kuning worms, could not be carried out, as all the moths when they came to be miscroscopi- cally examined were found to be diseased. I therefore had to take advantage of a fact which has been noted by Pasteur, that although pebrine is hereditary, still that not all the eges of a diseased mother will be infected. To carry out the suggestion contained in this observation, a number of small china cups were obtained, the least diseased eggs were used, and the worms on hatching out, were put four in each cup, and during their whole lives rigidly isolated from their fellows. The cups were fre- quently disinfected, and any worms which seemed diseased removed as quickly as obser ved. By these means a considerable number of quite healthy moths were produced. The microsco- pical examination, isolation of the worms and disinfection of the house and its contents were continued, and in the course of three generations, the disease entirely disappeared. This ex- periment has now been carried on for over nine months, and it goes far to prove that, given a healthy breed of worms to start with, silk culture could be successfully carried on in Perak, if proper precautions were taken to disinfect the rearing houses and apparatus, and to maintain the breed used for seed purposes in a CULTURE OF SILKWORMS. 11 healthy condition, by strict isolation and by submitting it to microscopic or other selection in the manner hereafter explained, PEBRINE AFFECTING WILD MOTHS IN PERAK. His Excellency the Governor some time back sent me, through the Acting British Resident, a number of the reports of the Indian Silk Committee, and in one of these papers 1t was in- incidentally mentioned that pebrine, the disease which has been causing such havoc in Perak, affects other genera of the lepidop- tera besides the genus to which the silkworms belong, and it occurred to me that an examination of the wild moths might be useful. With this object I began a microscopical enquiry, and on the evening of the Ist February found a common wild moth badly affected by pebrine. The bacteria were identical in form, size and refringence with those from the silkworms, with which they were carefully compared, and there appears no reasonable cause to lead to the supposition that they are not the same micro-organism, though the actual proof—viz., mocula- tion—is wanting, and rather hard to apply, with any hope of obtaining positive results. This unlooked for and disagreeable discovery clearly indi- cates that the disease is endemic in Perak, and that, although it may be eradicated from all the silkworms in the State, or a perfectly pure breed be introduced, yet they will always be subject to re-infection from coming into contact with wild pebrinous lepidoptera, or the virus emanating from these diseased insects. fo) It was previously concluded that, owing to the isolated posi- tion occupied by Perak in regard to silk culture, infection was only to be feared from outside, and that, eiven a healthy breed of worms and proper precautions against the introduction ‘of disease from China or India, that the worms would enjoy complete immunity from pebrine. This hypothesis is now apparently shown to be fallacious, and, instead of once eradicating the disease, it will he necessary to pursue a continuous course of selection of seed, if the cultivation is ever to be carried on suc- cessfully. CONDITIONS NECESSARY TO ENSURE SUCCESS. As the result of over two years’ observation and experiment on the growth of silkworms in Perak, I have arrived at the following conclusions. The houses used to rear the worms in should be small and detached from one another. They should not be too high, and be made fairly light. They should be used for only this one pur- pose and should not be used as dwelling-houses, nor stables, nor 12 CULTURE OF SILKWORMS. as stores for keeping cocoons. They should be subjected to thorough disinfection between the rearing of each brood, by fumigation with sulphur and washing all the trays, cocoomneg frames, tray-stands and baskets used to hold the leaves with a carbolic acid soap solution. The trays used in one house should not be moved to another house unless disinfected first. All the refuse leaves, excreta, dead worms and sweepings of the rearing houses should be removed from the houses daily, and burned at once. On no account should they be used as manure for the mulberries until after burning. The stands for the trays should be placed in the centre of the houses so that they can easily be protected from insects and be got at to disinfect, and if necessary, readily enclosed in netting. Houses of fifteen feet wide would be most convenient, with a six- feet six-inch stand down the centre, so as to use a double row of three-feet diameter trays six or seven tiers high, that is, that each fathom of length of tray stand would accommodate from 24 to 28 three-feet diameter trays, eiving an area of from 169 to 197 square feet. A house 46 feet by 15 feet would therefore give 1,379 square feet of tray surface, which would be sufficient for the production of from one-and-a- half to two pikuls of co- coons per brood, or say eight pikuls per year. The stifling, sorting, stormg and packing of the cocoons should be done as far as practicable from the rearing houses, and all refuse from these operations should be carefully burned. To be a success, a good variety of worm should be introduced, and apparently bombya Madrassi would be the most. suitable to the climate and conditions of Perak. I have already remarked on the inferiority of the bombya sinensis, so that it need not be gone over again here. Having obtained a good breed of worms, they should be sub- jected to careful treatment by the Pasteur system to eliminate any hereditary taint that they may have, before they are given to the cultivators. From what has already been said, it will be evident that it would be necessary to maintain a breeding estab- lishment for the supply of pure eggs. This should be some way from any other establishment, and special precautions should be taken to avoid infection from wild moths, by the use of wire netting to all windows and doors of the rearing houses. With care in this respect there would only remain the rather remote chance of infection by means of the mull verry leaves used as food, having been soiled by some diseased wild moth or caterpillar. This no possible means could be taken to prevent. As ereat difficulty has been experienced in India in the attempts ae th have been made, for some years past, by the CULTURE OF SILKWORMS. 1S Silk Committee to apply the Pasteur system to the multivoltine worms, I will state here what my experience has been, the way I have carried out the system and the plan which I propose for adoption on a large scale. The moths on coming out of the cocoons are allowed to pair, and in the evening are separated, the males being thrown away and the females bemeg placed each in a small cone of paper, one corner of which is then turned in so as to close its mouth. These paper cones are strung up and the eges laid in them. On the fifth or sixth day after laying, the moths are each taken and crushed in little china cups with a glass pestle. A drop of the fluid is transferred to a glass slide and a cover glass put over it. These shdes are then examined with a quarter-inch object glass and high power eye-piece, giving a magnifying power of 6350 dia- meters. The eges of all diseased moths are then destroyed, and the healthy ones “only reserved for breeding. On two occasions, starting with highly pebrinised worms, I eradicated the disease in from three to four generations by the above course of pro- cedure. PROPOSED SYSTEM FOR PASTEURIZING MULTIVOLTINE SILKWORMS. The selection, by the microscope, of a large number of eges, in the way above described, is a commercial impossibility, as there are only six or seven working days between the laying of the eggs and the hatching of multivoltine worms, instead of about as many months in the case of the annual silkworms cultivated in Kurope. My plan for overcoming this difficulty is to maintain a breed of say 3,000 worms, which for convenience may be called “firsts.” This breed is to be kept distinct and to be microscopically selec- ted every brood. Our microscopist could examine all the female moths of each brood of this number of worms, between the lay- ing and hatching of the eges. A certain number of the eges from the best cocoons would be put aside for the next generation of ‘firsts,’ and the remaining eges would be reared in separate houses, in which strict sanitary precautions would be maintained. This brood, which would not be microscopically selected, may be called “seconds.” On attainmg maturity these ‘ sec- onds”’ would lay, and it is their eges which would be given to the cultivators. They would therefore be always only once removed from the “first” or microscopically selected eges. Tf 1,200 female moths out of the 3,000 above-mentioned were passed at a 14 CULTURE OF SILKWORMS. selection of “firsts,” they would yield, say, 240,000 eggs,* or 120,000 female “ scconds,” which again would yield 24 millions of eggs for distribution. This number of worms would give 16-458 tons of “ green” cocoons, or at four broods per annum, say 64 tons, as the outcome of the work of a single microscopist for a year. This is as much as a hundred mic roscopists could do, with multivoltine worms, if working by the ordinary method of selection as practised im Europe. The whole system depends on guarding from external sources of contagion the generation ehter that which has been proved to be free from disease by microscopical examination. To do this, cleanliness, the free use of antiseptics, isolation, and the growing of the food in a place where it will not be infected by rie althy worms, are the main points to be attended to. As Ai “precautionary measure, the “firsts”? might be divided advan- tageously, and kept m two separate houses. From time to time it might be necessary to introduce fresh blood into the breed, and for this purpose the fresh worms should be microscopically selected for four or five generations before mixing them with the original “firsts,” being kept during their probation in a house isolated from all the others. It may be mentioned here that I have found that a single selec- tion, never mind how carefully it is done, 1s insufficient to elim- inate pebrine from a race of worms. Therefore it follows that it is useless to attempt to produce “seconds” until the “ firsts” have been thoroughly purged of all traces of disease, by repeated selections. In an establishment such as is here suggested, the micro- scopist would be the only highly paid man. All the other work could be done, after a little time, by ordinary coolies, so that the cost of maintenance would be comparatively unimportant, and the eggs could be supplied at a low price. I venture to think that this system, if carried out properly, will do for the multivoltine silkworms of the tropics what the system practised in Hurope has done for the annual silkworms of temperate climates. SELECTION BY LONGEVITY. Mr. R. Blechynden communicated to me a plan he has been trying, to effect the selection of healthy worms for breeding * A female of bombya sinensis J find lays on an average 355 eggs, weighing 2°414 grains; 160 moths would lay one ounce of eggs, the standard ounce being 15 grams or 385°8 grains. In the above estimates it has been assumed that euch moth will produce only 200 worms. CULTURE OF SILKWORMS. 5 purposes, without the use of the microscope. The system consists of the placing of each female moth under a small cap inverted on a sheet of paper, on which it lays its eggs. The cups are suffered to remain with the eggs and moth beneath them until the eggs begin to hatch, and the eggs of all those moths which are alive at that time are taken to be healthy, and those which have died prior to the hatching of the eggs are thrown away as unhealthy. I have experimented with this system, and there appears to be a good deal to be said in favour of it; the moths which survive being almost without exception healthy ; ; though it by no means follows that all that die early are diseased. To deal with the same number of moths as mentioned above would, however, involve the manipulation of about 150,000 china cups, and would require over 4,000 square feet of table surface to put them out on. It has the great disadvantage that the eggs cannot be distributed as eggs, and that the young worms could only be sent a short distance from the breeding establishment. In the system advocated above, either the cocoons of the “seconds,” or their egos could be distributed, and there would be plenty of time to send them long distances. CULTIVATION OF MULBERRIES. From the experience acquired in Larut it would appear that the best way to cultivate mulberries would be to fell the jungle, burn and clear it as if going to plant padi or coffee. Then put in the mulberry cuttings, or better, the young plants, previously raised in a nursery, at distances of 12 feet by 12 feet, that is, 302 plants per acre. If it is wanted to begin picking early, they might be planted at 6 feet by 6 feet, or 1,210 per acre,and every other row, and the intermediate bushes of the remaining rows bemg picked at first, the bushes which had been picked when young being after wards cut out, as the unpicked ones grow larger and require more room. If these latter are allowed to grow to 6 feet in height and to become large spreading bushes, they will last for years; but when grown as the Chinese erow them, which is an attempt to violate all the conditions which the plant naturally requires to be fulfilled, they are very delicate and susceptible to the influence of over-picking, disease or neglect of weeding, and are very apt to die out. They should never be picked too close, as it is always to be remembered that the leaves are the organs which supply a plant with its pr incipal food, that is, the whole of its carbon, and indirectly with all its other food, as without the leaves to exhale the watery portion of the sap, the roots cannot absorb moisture from the soil, and unless they absorb water they cannot acquire nourishment from the soil, as the water is the medium in which the nutritive parts of the earth are conveyed to the plant through the roots. 16 CULTURE OF SILKWORMS. The bush varieties of mulberry have hitherto been only con- sidered, but it appears that the tree varieties are in some situa- tions to be preferred, or at least, might be advantageously planted in conjunction with the bush var ieties. They need not be weeded after attaiming some size, which to a Malay is a great consider- ation. They can be planted amongst other trees, “and as hedges to fields, kampongs, etc. The worms appear to eat the leaves, and thrive on them. I have found no difference in this respect between the two varieties, except that the bush mulberry is more suited to the worms when very young, as the leaves are much softer. The mulberries can readily be propagated by cuttings. These are best made when the plant is at rest, though they may, with care, be got to strike at any time of the year. Pieces about a span long are the best, and they should be cut at the bottom end, close beneath a joint, otherwise they are very apt to damp off. They grow best when planted upright, and with not more than three inches of the cutting beneath the surface of the ground. If treated as the Chinese and Javanese usually treat cuttings, that is, planting them diagonally with three-quarters of the whole length of the slips beneath the ground, not one in ten will strike ; whereas if planted as recommended, not one in ten will fail. Apparently, four or five broods of silkworms could be raised in the ‘year. The mulberry appears to have two growing seasons during each year in Perak, but sufficient experience has not yet been acquired to enable it to be definitely stated when it would be best to rear the broods. The refuse from the rearing houses should all be burned before it is returned to the land as manure, as it would appear by the experience gained in India that the disease germs contained in this refuse get on to the leaves and infect worms fed on them. This can be easily understood when it is remembered that the germs retain their vitality for a period of at least eight months. LABOUR. The main condition that must be fulfilled to ensure the successful breeding of silkworms in Perak, or anywhere else for that matter, is employment of cheap labour. The mining in this State has raised the wages of all classes, particularly amongst the Chinese, and though I have not been able to collect any reliable information on the subject, I do not think that silk could be produced by means of Chinese labour at a price that would be remunerative. If it is to be successfully grown, I believe it would be by the Malays, as amongst them the wages are lower, and women and children could be employed for all the light portions of the industry; which they can do not only cheaper, CULTURE OF SILKWORMS. 17 but actually better than men. The Kuala Kangsar and Krian districts are the most suitable, as in both places there is a com- paratively thick Malay population, and very little mining near to raise the price of labour. If some Malay chief of weight could be induced to exert his influence on the people, silk culture might, I believe, easily be established amongst the Malays. It is essentially a peasant industry. To carry out this suggestion it would be necessary to form nurseries of mulberries in the district chosen for the experiment, so as to be able to supply plants to the Malays, who should be induced to plant them in their kam- pongs—not only those who are intending to rear the worms, but others, who could afterwards sell leaf to the actual keepers of the worms. On no account should the Ayer Kuning mulberries be used to propagate from, as the leaf disease would be propa- gated at the same time. Having secured the planting of the mulberries, the next step would be to show, by an actual demonstration in the district, the way in which the culture is to be carried on. Pure eges would, of course, have to be supplied, but by the system already explained in detail, half a day’s work with the microscope at each brood would be sufficient to supply all the egos needed for a long time to come. The silk when produced should either be reeled locally by the cultivators, or the cocoons should be sent to Europe for sale. Tf reeled locally it must be done well, or the price is seriously reduced. Reeling is almost always done by women, and here again the only people who would be suited to the work would be the Malays. TAIPING, September 21st, 1892. EXPLANATION OF PLATH. Fie. 1. Transverse section of mulberry leaf, through the centre of a disease spot. Magnified 51 diameters. Fre. 2.