I found this passage in my book Hair, its Care, Diseases and Treatment from 1879. I was perusing and saw an interesting piece about how hair grows. Please consider the following:
EXIT FROM THE FOLLICLE
At the first formation of the hair-cylinder it does not issue point first from its follicle, but it is bent over upon itself, so that a loop gradually pushes its way through the follicular opening, and then, from its elasticity, the shaft straightens itself out. Indeed, it is the law of almost all growths, that the point does not issue direct from the parent-cell or follicle, but is bent downwards till the exit-making loop is formed... Sometimes, for various reasons, prominent among which is the sealing of the follicle with sebaceous matter, or its being covered over by the scales of scarf-skin, or the outer walls adhering together, the hair cannot make its exit at all; in this case it keeps on its growth--for the papilla, as long as blood is sent to it in proper condition, never ceases its work--and doubles more and more upon itself until the follicle is fully distended.
-------pgs. 24 & 25
I never learned this in beauty school. In fact, I don't know that it was even a part of any anatomy class I have ever had. I had to read a book from two centuries ago, to find this out. I have determined the case to be true, especially after waxing. I find that I get, what are commonly called ingrown, hairs when the new growth is making its way to the surface of the skin. Without having a hair already extruding through the pore, as in regular growth and shedding, the skin can close over the budding root and follicle. When that happens the hair can curl in on itself and never break through the skin surface. If I catch it early in the process, I just take a pair of tweezers and break the skin and get the hair up and out. If I am a bit late, there can be a bit of a inflammation reaction and an ingrown hair.
Isn't this the most fascinating of ideas. And I am only 140 years late to the game. Sometimes, the past has the answers and we just have to be smart enough to look it up.