I left them alone, and began to watch what they would do.
The eldest worms climbed to the ceiling, scattered about, crawled in all directions, and began to draw out single threads in various directions. I watched one of them. It went into a corner, put forth about six threads each two inches long, hung down from them, bent over in a horseshoe, and began to turn its head and let out a silk web which began to cover it all over. Toward evening it was covered by it as though in a mist; the worm could scarcely be seen. On the following morning the worm could no longer be seen; it was all wrapped in silk, and still it spun out more.
Three days later it finished spinning, and quieted down. Later I learned how much web it had spun in those three days. If the whole web were to be unravelled, it would be more than half a mile in length, seldom less. And if we figure out how many times the worm has to toss its head in these three days in order to let out all the web, it will appear that in these three days the worm tosses its head 300,000 times. Consequently, it makes one turn a second, without stopping. But after the work, when we took down a few cocoons and broke them open, we found inside the worms all dried up and white, looking like pieces of wax.
I knew that from these larvæ with their white, waxen bodies would come butterflies; but as I looked at them, I could not believe it. None the less I went to look at them on the twentieth day, to see what had become of them.
On the twentieth day, I knew, there was to be a change. Nothing was to be seen, and I was beginning to think that something was wrong, when suddenly I noticed that the end of one of the cocoons grew dark and moist. I thought that it had probably spoiled, and wanted to throw it away. But then I thought that perhaps it began that way, and so I watched to see what would happen. And, indeed, something began to move at the wet end. For a long time I could not make out what it was. Later there appeared something like a head with whiskers. The whiskers moved. Then I noticed a leg sticking out through the hole, then another, and the legs scrambled to get out of the cocoon. It came out more and more, and I saw a wet butterfly. When all six legs scrambled out, the back jumped out, too, and the butterfly crawled out and stopped. When it dried it was white; it straightened its wings, flew away, circled around, and alighted on the window.
Two days later the butterfly on the window-sill laid eggs in a row, and stuck them fast. The eggs were yellow. Twenty-five butterflies laid eggs. I collected five thousand eggs. The following year I raised more worms, and had more silk spun.