Page:Popular Science Monthly Volume 67.djvu/166

166 Extraordinary as were the two cases of aggregate phylogenetic plant mutation which came under my observation, they are no more wonderful as natural phenomena than are the numerous cases of sudden and aggregate atavic reversion of previously constant and heritable fruit characters which have been mentioned in this and other publications. Indeed, among tomatoes, the aggregate occurrence of both plant mutation and atavic fruit reversion appears to be quite as normal as does their separate or individual occurrence. In both kinds of these cases, although their results are so different, the initial change has occurred in the germ cell of each of the seed ovules which gave origin to the affected plants. Both kinds are of mysterious, but doubtless natural, origin. Still, I can make no suggestion as to what may be the nature of either the determinate, predisposing or exciting cause in any of these cases.

It is not necessary, but it may not be inappropriate, to say that the foregoing paragraphs have not been written from a biometrical point of view, but from that of an old time naturalist. The principal facts which are there recorded have presented themselves to me with more force than I feel able to present them to others. I am still greatly impressed with their remarkable character, especially because they are not in accord with my own former views. Some of them also are known to be at variance with commonly accepted views of horticulturists, but I present them all with full confidence in their accuracy. Indeed, I do not admit the possible occurrence of any error that could have been instrumental in producing any of the phenomena which are here recorded.

Notwithstanding the peculiar features of these two cases of sudden mutation in the genus Lycopersicum, I assume that in their essential nature they are to be classed with those cases of mutation which have been observed in the genus Œnothera by Professor de Vries, and which he has used in demonstrating his theory of mutation. In his experiments with those plants, popularly called evening primroses, he repeatedly observed, in different years, the origination by sudden mutation of a few individual plants of one and the same species among the numerous progeny of the mother species. He also observed the similarly sudden and rare mutation of several new species from a mother species, but he has not reported any case of mutation of all the progeny of any one plant of a mother species; much less the progeny of a whole crop of plants, such as I have observed with reference to the genus Lycopersicum.