An introduction to the topic is available in Wardman  – An Introduction to Textile Coloration in this section on the cotton fibre. It will also be useful as an introduction to the chemistry of cellulosics which is covered in the next lesson.

For more detailed information on the structure of cotton as well as the other cellulosics then take a look at this by Burkinshaw in Physico Chemical aspects of Textile Coloration – Cellulosics. Further pages form this chapter will be provided where relevant.

This provides further details on the fine structure of cellulosics

There are some very good images of the structure of cotton available on the internet which clearly show the direction of the fibrils so do take a look around to be clear on various aspects that you are taught.