The second theory put forward in an attempt to correct the issues surrounding cellulose lengthening during crystallisation is that hemicelluloses are trapped between the fibrils and cause them to bend and longitudinally contract \citep{Mellerowicz_2008}. Mechanically this is very similar to the lignin swelling hypothesis. By causing the MFs to no longer run straight, instead they have to use some of their length to deviate passed a cluster of hemicelluloses consequently shortening the over all distance the fibril can cover.