Yes Böckchen, I know that they had rather small horses, the Lituanians, the Polish and the different Russian groups and I am thinking of the Tarpan, which some say is part of the domesticated horse. And the Tarpan was a small, pony like horse only 120 cm high. And according to Wikipedia it’s blood runs in many pony races veins today, so yes, maybe Madlener was right after all.
In any case, his (and Frank's) horses are very much alive and a pleasure to put paint on.
