Hippocrates on semen; a mill rod; reflected colour
Three notes: the origin of seed, a pivoting mill rod, and opaque bodies taking colour
The sheet gathers three unrelated notes. At the top, written upside down, is an account after Hippocrates of how the seed derives from the brain, lung and testicles of the parents, where a final concoction takes place, all other members feeding it their substance by sweating. A short caption beside a pen drawing labels a pivoting rod fitted with a catch, meant for a mill. A note in pen states that the surface of any opaque body will be tinged with the colour of the bodies placed against it.
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Hippocrates on the origin of the seed
Following Hippocrates, the note says our seed derives from the brain, the lung and the testicles of our parents, where the final concoction takes place. All the other members contribute their substance to this seed by a kind of sweating, since no direct path can be shown by which they might reach it. It is a note on generation and embryology.
Pivoting rod with a catch, for a mill
A short caption labels a pivoting rod fitted with a stop or catch, noting it is for the mill. The pen drawing above shows a horizontal bar ending in a cross-shaped fitting with a pivot pin at its left end.
Opaque surfaces take the colour of nearby bodies
A note in pen states that the surface of any opaque body is receptive and will be tinged with the colour of the bodies set against it. It is an early statement of reflected colour, a principle central to Leonardo's painting theory.