Sericulture

As soon as the mating is over, work is begun on the micro scoping of the seed which has been laid. In the case of selection for cellular seed, each bag is emptied of its contents, the seed is washed in water to free it from the remains of the dead female and a few seeds are crushed and placed on a slide for examina tion. If the microscope tells no tale of disease, that particular laying is passed. If traces of disease are found, the bag and its contents are burned. In the case of seed not to be used for re production but only to be distributed for producing cocoons for silk, called industrial seed, each rearing is kept separate and the contents of all the bags of one rearing are emptied out together.

This heap of seed is washed as before, is well mixed and half a dozen samples are taken, crushed and examined as before. If disease is detected, further sam ples are taken to determine the extent of it. If not more than 5% of disease is apparent, the rearing passes; if more, it is en tirely destroyed. In this way all the eggs are gradually cleared through the microscoping room, a further washing takes place and, after the seed is dry, it is done up in small gauze bags in weights of 1 oz., oz. and oz. These, in turn, are placed in per forated cardboard boxes and are ready for distribution to rearers the following season, the cellular seed being kept separate for se lected rearers for a further cycle of reproduction.

The expert's task is not finished with the production of sound and healthy seed. He is also concerned with the cross-breeding of different varieties with a view to a higher yield of silk in the cocoons for reeling, to creating hardier races for different con ditions of climate, to improving the cocoons of one part of the world by crossing the moths with those from another--an endless succession of problems for the propagation of sericulture in general.

That the silkworm is subject to many serious diseases is only to be expected of a creature which for upwards of 4,000 years has been propagated under purely artificial conditions, and these most frequently of a very insanitary nature, and where not the healthy life of the insect, but the amount of silk it could be made to yield, was the object of the cultivator. Among the most fatal and disastrous of these diseases with which the cultivator had long to grapple was "muscardine," a malady due to the development of a fungus, Botrytis bassiana, in the body of the caterpillar. The disease is peculiarly contagious and infectious, owing to the de velopment of the fungus through the skin, whence spores are freed, which, coming in contact with healthy caterpillars, fasten on them and germinate inwards, giving off corpuscles within the body of the insect. Muscardine, however, has not been epidemic for many

years.

The Pebrine Epidemic.

About the year 1853 anxious atten tion began to be given in France to the ravages of a disease among silkworms. This disease, which at a later period became known as pebrine—a name given to it by De Quatrefages, one of its many in vestigators—had first been noticed in France at Cavaillon in the valley of the Durance near Avignon. Pebrine manifests itself by dark spots in the skin of the larvae; the eggs do not hatch out, or hatch imperfectly; the worms are weak, stunted and unequal in growth, languid in movement, fastidious in feeding; many perish before coming to maturity; if they spin a cocoon it is soft and loose, and moths when developed are feeble and inactive. When sufficient vitality remains to produce a second generation it shows in increased intensity the feebleness of the preceding. The disease is thus hereditary, but in addition it is virulently infectious and contagious. From 1850 onwards French cultivators were com pelled, in order to keep up their silk supply, to import graine from uninfected districts. The area of infection increased rapidly, and with that the demand for healthy graine correspondingly ex panded, while the supply had to be drawn from increasingly re mote and contracted regions. Partly supported by imported eggs, the production of silk in France was maintained, and in 1853 reached its maximum of 26,000,000 kilos of cocoons, valued at 117,000,000 francs. From that period, notwithstanding the im portation at great cost of foreign graine, reaching in some years to 6o,000 kilos, the production of silk fell off with startling rapidity: in 1856 it was not more than 7,500,000 kilos of cocoons; in 1861 and 1862 it fell as low as 5,800,00o kilos; and in 1865 it touched its lowest weight of about 4,000,000 kilos. In 1867 De Quatrefages estimated the loss suffered by France in the 13 years following 1853, from decreased production of silk and price paid to foreign cultivators for graine, to be not less than one milliard of francs. In the case of Italy, where the disease showed itself later but even more disastrously, affecting a much more extended in dustry, the loss in io years De Quatrefages stated at two milliards.