C. Janet observed that in a nest of Lasius alienus, established by a single female, the first workers emerged from their cocoons on the 102nd day.
Crowding of positions must now be guarded against, to prevent the spinning of double cocoons (doupions) by two worms spinning together and so interlacing their threads that they can only be reeled for a coarser and inferior thread.
From that period, notwithstanding the importation at great cost of foreign graine, reaching in some years to 60,000 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 5,800,000 kilos; and in 1865 it touched its lowest weight of about 4,000,000 kilos.
He found corpuscles in Japanese cocoons and in many specimens which had been preserved for lengthened periods in public collections.
At intervals of five days after spinning their cocoons specimens were to be opened and the chrysalides examined microscopically for corpuscles.