At the far end of the laboratory, there was a blackboard on which one of the men was drawing something that looked like hexagonal molecules, linking them together.
"Syndrome"
Thomas Hoover
The ommatidia are more nearly circular than hexagonal in outline, and are variable in size, some being considerably larger than normal.
"Sex-linked Inheritance in Drosophila"
Thomas Hunt Morgan Calvin B. Bridges
This central drop is also deformed, and has assumed a more or less hexagonal form, under the influence of the attraction of the six smaller ones.
"The Mechanism of Life"
Stéphane Leduc