Yesterday I visited Dhaka's Science Laboratory and, while waiting for a meeting, had a fascinating discussion with a young scientist about silk production.
Silk is produced in Rajshahi. Why Rajshahi? Because that's where most of the mulberry (toot in Bangla) trees are. And mulberry leaves are the food of silkworms.
The young silkworms are fed these mulberry leaves, which they apparently eat day and night. Then they build a cocoon around themselves using their saliva (entering the pupa stage.) As they spin the saliva round and round it hardens to become silk thread. An adhesive is also created from the saliva at the same time - this adhesive sticks the threads together.
If silkworm's lifecycle is allowed to proceed naturally, then they grow into moths inside this cocoon, breaking the cocoon and flying out. Unfortunately breaking the cocoon creates tears in the thread.
So instead, when the cocoon reaches the optimum size, it is boiled. This kills the worm inside. It also removes the adhesives that hold the silk threads together.
Now the unbroken thread of the cocoon is pulled, unravelling the cocoon. Incredibly, the thread from one cocoon can be up to 250-300m long. (That must have been one dizzy worm, spinning around so many times to create its cocoon!) This silk thread is woven together to make Rajshahi silk.
Not all cocoons are boiled. A fraction are saved and used for breeding purposes for the next generation. The scientist guessed the length of the life cycle to be 2-3 months.
While we were waiting we also discussed the environment. I mentioned to him my concern about the possible compromise of the food chain with chemical impurities with our rapid industrialization. He said yes, that was inevitable, and the most likely and damaging culprits were heavy metals. Eg, lead in paints and dyes, tungsten, etc. Arrgh. This lab was working on creating new natural dyes. But they had doubts about economic viability.
Science Laboratory has many divisions working on research, testing, prototype building, better processes, certification, and other types of work. The scientists I met there were knowledgeable and proactive. Do we as a nation make optimum use of it?
Thanks to my friend Rahim for making this trip possible.