The authors point out there's a bit of a mystery about precisely which hole Colombo was poking with his Italian probe. It might, in fact, have been the more posterior opening identified by the 17th-century Dutch anatomist Isbrand van Diemerbroeck, who found, in Colombo's groove, "the hole of the anus." Your brain's anus, incidentally, is what we'd now call the common posterior opening of the midbrain's aqueduct, which spills into the third ventricle. There are so many defecation-related puns about intelligence to be made here that my mind is cramping up, so, shit, I'll just leave that part up to you assholes.
Now, van Diemerbroeck didn't just see lady bits in the brain; if anything, he and his fellow anatomists envisioned it as an essentially hermaphroditic organ. After all, not only did it have a vulva cerebri, it also possessed a distinctive penis cerebri. René Descartes may have celebrated the pineal gland as the "seat of the soul," but for the less metaphysically minded van Diemerbroeck, as well as one of Descartes' contemporaries, the Danish physician Thomas Bartholin, that structure was more like a penis. This metaphor may have its roots, explain Olry and Haines, in the position of the gland above and between the brain's colliculi, which had already been compared with testicles (as, perhaps, the original "hanging brain").
This cockeyed term, penis cerebri, proved too embarrassing for future scholars and quickly shrank into disuse. Yesterday's penis is today's soulless pineal gland (a stiffer term, to be sure). By the mid-18th-century in France, a real buzz-kill of an anatomist by the name of Jacques Bénigne Winslow was already looking back in disgust at his forebears' indelicate classifications; the ancients, he thought, had their heads in the gutter when it came to what was in their heads. Winslow held these founding fathers of the neurosciences in particular disrepute for their having seen buttocks (eminentiae natiformes) and testicles (eminentiae testiformes) in the colliculi. "The names that were given to these tubercles are very impertinent, and have no resemblance with the things they were derived from." Others begged to differ, and scholars continued to refer to the buttocks and testicles in our brains for centuries after Winslow huffed and puffed about the matter, even into the 20th century. Eventually, however, academic prudery eclipsed asinine antiquarianism.
Still, a spunky remnant of those lost days of brainiac debauchery did slip into the present-day vocabulary. According to Olry and Haines, the glandular portion of the pineal gland can be traced back to its bulbous terminological predecessor, the glans penis. Today we know that the pineal gland produces melatonin, a chemical central to regulating your sleep-wake cycle. So the next time you have jet lag, blame it on your penis.
Olry and Haines weren't the first to scratch their heads over this lurid labeling of our neuroanatomical regions. Joining the prudish Winslow in his disdain, the French anatomist Joseph Auguste Aristide Fort observed in 1902 that the anatomists of past centuries "enjoyed giving indecent names to the different parts surrounding the third ventricle." But Olry and Haines did show exactly how these Renaissance anatomists cast their libidinous eyes upon the gray matter and saw not the glistening engine of our thoughts, but rather our private parts.