Examination of the cross-sections has shown that in the earlier phase he used exclusively cobalt blue, available from 1802, his habitual choice during the 1870's and early 1880's, but in finishing and revising the composition he used only artificial ultramarine which came in use in the 1870s.
A common misconception with this is that nits and lice are the same thing. In fact this is not the case, the truth is: Lice are the tiny grey or brown insects that are found in the hair. The lice are about the size of a small seed (i.e. Sesame seed) and cling to the hair staying close to the scalp which they live off.
Crawling Lice: Nymph or adult lice (as opposed to eggs/nits) Infestation: Lice inhabiting the scalp and hair. Nit comb: A fine-toothed comb that helps remove nits and crawling lice from the hair. Insecticide: A chemical that kills insects. Over-the-counter insecticides for lice are also known as pediculocides.