We thus see that in all parts of the world breeds of the horse as different as possible, when of a dun-colour (including under this term a wide range of tint from cream to dusky black), and rarely when of bay, grey, and chesnut shades, have the several above-specified stripes. Horses which are of a yellow colour with white mane and tail, and which are sometimes called duns, I have never seen with stripes.[133] From reasons which will be apparent in the chapter on Reversion, I have endeavoured, but with poor success, to discover whether duns, which are so much oftener striped than other coloured horses, are ever produced from the crossing of two horses, neither of which are duns. Most persons to whom I have applied believe that one parent must be a dun; and it is generally asserted, that, when this is the case, the dun-colour and the stripes are strongly inherited.[134] One case has fallen under my own observation of a foal from a black mare by a bay horse, which when fully grown was a dark fallow-dun and had a narrow but plain spinal stripe. Hofacker[135] gives two instances of mouse-duns (Mausrapp) being produced from two parents of different colours and neither duns. I have also endeavoured with little success to find out whether the stripes are generally plainer or less plain in the foal than in the adult horse. Colonel Poole informs me that, as he believes, "the stripes are plainest when the colt is first foaled; they then become less and less distinct till after the first coat is shed, when they come out as strongly as before; but certainly often fade away as the age of the horse increases." Two other accounts confirm this fading of the stripes in old horses in India. One writer, on the other hand, states that colts are often born without stripes, but that they appear as the colt grows older. Three authorities affirm that in Norway the stripes are less plain in the foal than in the adult. Perhaps there is no fixed rule. In the case described by me of the young foal which was narrowly striped over nearly all its body, there was no doubt about the the early and complete disappearance of the stripes. Mr. W. W. Edwards examined for me twenty-two foals of race-horses, and twelve had the spinal stripe more or less plain; this fact, and some other accounts which I have received, lead me to believe that the spinal stripe often disappears in the English race-horse when old. On the whole I infer that the stripes are generally plainest in the foal, and tend to disappear in old age.