See also the 1895 comment from Liberty Hyde Bailey that I just posted to 'Perle des Jardins'.

Mystery is added to the mix in that it appears that, about the same time as the Ritter/Hill rose showed up, Nanz & Neuner possessed not only a white Perle but also a pink one (see below), though unlike the case with Ritter and E.G. Hill, there's no statement to the effect that either actually originated with N&N. Reference in the below to yet another 'White Perle' originating in England further complicates the situation:

"Nanz & Neuner, Louisville, Ky., send us blooms of two sports from Perle des Jardins. One is white in color, and named 'White Perle des Jardins,' the other is pink and named 'Pink Perle des Jardins.' The blooms received were about the size and shape of a small Perle, but as they were presumably from very young plants it may not be just to condemn them on account of small size. Both were fragrant and the foliage of each had the characteristics of the yellow Perle. Of course time only will demonstrate whether they will be of value to the florist, but sports from the Perle are certainly worthy of a thorough trial and we shall be glad to hear the result of such trial. In view of the fact that a sport from the Perle, which originated in England, has been named 'White Perle' it might be well to change that of this American sport." --American Florist, vol. 4, 1889, p. 470.