regarding the fourth that the parts of the bones of the leg forearm and the like are increased. if it were due to the penetration of food then the larger bone that needs more food would have more parts. if that were the case then the upper ulna would not have two appendages and the lower ulna would not be much larger than it although it has one appendage.
وعن الرابع أن تكثير أجزاء عظام الساق والساعد ونحوها. لو كان لنفوذ الغذاء لكان العظم الأكبر المحتاج إلى غذاء أكثر أجزاؤه أكثر. ولو كان كذلك لما كان الزند الأعلى ذا لاحقتين والزند الأسفل أعظم منه بكثير وهو ذو لاحقة واحدة.