In reply to JFT:
I can't actually see anything but if you're worried, clean it out thoroughly with warm water and an old toothbrush, allow to dry (NOT on the radiator or somewhere hot). Once dry, add a boot wax like Zamberlan's hydrobloc, Scarpa's HS12, granger's G-wax or meindl's sport wax. Important that it's not dubbing. I say clean and dry because if not, any bacteria in the crack will be trapped under the wax and eat more of the leather. the above creams and waxes help nourish the leather as well as protect it.
If you're really worried about it, shoe goo might help, but again clean the crack thoroughly first or you'll be doing more harm than good.
both of these approaches will only prolong the inevitable.
I hope this helps.