We do not know whether Karl's mother or the grandmother insisted on keeping the baby wrapped in swaddling clothes during the first year of his life. It is highly probable that later on the child had been kept out of sunshine on account of the sick eyes. If the closure of the fontanels is delayed as the skull develops it becomes broader and flatter than normal. It used to be called 'caput quadratum', and the prominent shape of the front, the 'bossing', is sometimes called 'frons quadrata'. Nowadays the basic prophylactic measures to prevent rickets are well known.
Vitamin D is found in fish liver oils, egg yolk and milk.
Butter, eggs and fatty fish such as herring, mackerel and salmon contain vitamin D. Vitamin D is also manufactured in the skin in the presence of sunlight. From this simple rule we can deduce that it was not so in baby Karl's case. There was little milk available and little Karl was kept away from the sunshine because of his sore eyes. Since the 18 th century it was known that cod-liver oil was of help in rickets. Children who could not take cod liver oil were prescribed halibut-liver oil.