160 POPULAR SCIENCE MONTHLY. 



Extraordinary as were the two cases of aggregate phylogenetic plant 

 mutation which came under my observation, they are no more wonder- 

 ful 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 muta- 

 tion 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 horticultur- 

 ists, but I present them all with full confidence in their accuracy. In- 

 deed, 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 (Enothera by Professor de Vries, and which 

 he has used in demonstrating his theory of mutation.* In his experi- 

 ments with those plants, popularly called evening primroses, he re- 

 peatedly observed, in different years, the origination by sudden muta- 

 tion 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 refer- 

 ence to the genus Lycopersicum. 



* See ' Die Mutationstheorie,' von Hugo de Vries, Volumes 1 and 2, Leip- 

 zig, 1901, 1902; 'The Mutation Theory of Professor de Vries,' by Charles A. 

 White, Smithsonian Report for 1901, pp. G31-640; and 'A New Theory of the 

 Origin of Species,' by A. Dastre, Smithsonian Report for 1903, pp. 507-517. 



