First of all, to truly be a North-or-South-going Zax, it must always be going, and in the proper direction. So perhaps the Zax simply never arrives. Asymptoticly, they could simply approach but never arrive. [I will not here consider the possibility that Zax actually meander, like layabout cousins who constantly phone along a menadering path threatening to show up for a visit, but thankfully never quite managing to arrive.]
However, this brings to mind event horizons, which suggests the possibility of ``Zax Holes''. If, as is postulated with black hole/white pairs, there were then an equivalent ``Xaz Hole'', the Zax would approach the appropriate pole, fall into the Zax Hole, and instantaneously (or close enough as makes no nevermind) pop out at the appropriate Xaz Hole, still moving in the appropriate direction. In this case, I forsee the discovery of the North Zax Hole and the South Xaz Hole revolving about each other at the North Pole, and the South Zax Hole and the North Xaz Hole revolving about each other at the South Pole.
If this is the case, perhaps the Zax are fully self-sustaining, in which case a lifetime of celibacy, regardless of its impact upon the Zax personality (it has yet to be proven that Zax, for instance, have hormones) would not necessarily affect the Zax population.
The North-going ZaxOf course, inevitably some Zaxen must be lost to extreme wear and tear, whether by natural causes (tornados, rust, polar bears, discomboobulation, thermal overexcitement at the polar approach) or unnatural causes (mugging, car-jackings, repossessions, forfeiture, congressional hearings, putsches, overexposure to John Denver, Spam).
Approaches the Pole,
Accelerating, falls
Into the Zax Hole!
Before he can blink,
He pops out the Xaz Hole,
Decelerates fast,
And leaves the South Pole.
His brother-in-law,
At the other Extreme,
Does a similar thing,
Causing Nature to beam
At her own symmetry
Midst the Ice and the Snow
(Which we don't eat if green
For that's where the Zax go).
However, there is no reason to believe that such a being so obviously from another dimension should require procreational capabilities along the lines of your average bipod. They may just as well procreate by thought wave, pollen carrying bees, or Government Fiat.
Copyright 1989-1994 Miles O'Neal, Austin, TX. All rights reserved. Miles O'Neal <roadkills.r.us@XYZZY.gmail.com> [remove the "XYZZY." to make things work!] c/o RNN / 1705 Oak Forest Dr / Round Rock, TX / 78681-1514