Reproductive isolation from a cross between a horse and a donkey or between a mare and a donkey, respectively. These animals are nearly always sterile due to the difference in the number of chromosomes between the two parent species. Both horses and donkeys belong to the genus "Equus", but "Equus caballus" has 64 chromosomes, while "Equus asinus" only has 62. A cross will produce offspring (mule or hinny) with 63 chromosomes, that will not form pairs, which means that they do not divide in a balanced manner during meiosis. In the wild, the horses and donkeys ignore each other and do not
Equus (play) this off when he hears the horses making noises in the stables beneath, which he decides is the reason for his inability to get an erection. Jill tries to ask Alan what the problem is, but he shouts at her to leave. After Jill dresses and walks out of the stables, the still nude Alan begs the horses for forgiveness, as he sees the horses as God-like figures. "Mine!...You're mine!...I am yours and you are mine!" cries Equus through Dysart's voice, but then he becomes threatening: "The Lord thy God is a jealous God," Equus/Dysart seethes, "He sees you, he