36 
into existence. Thus the curves expressing heights of - nanella 
group themselves about the mean value of 22.81 + 1.02 cm. 
with a range from 7 to 35 cm., while those of O. Lamercon 
group themselves about the mean of 88.68.55 cm. with a 
range from 77 to 96 cm. e number of branches per individual 
of Lamarckiana ote from 11 to 25 while that of radrznervis 
was 34 to 62. The actual discontinuity is somewhat more fully 
expressed, however, by a comparison of the numerous features 
which elude measurements. The wide range of variability of the 
newly arisen forms is in itself one of their distinctive characters. 
It might be supposed that the variability of the new forms was 
the result of selection by the experimenters, but it is evident that 
whatever unconscious selection may have taken place in the cul- 
tures would have been directed to.a diminution of the range of 
variability. 
The chief interest in these studies lies in the fact that the ap- 
pearance of new qualities or characters of plants has been brought 
under actual observation, and that new species have been seen to 
arise under the eye of the experimenter. Previously to the 
epoch-making investigations of Professor DeVries upon the sub- 
ject a few species had been known to arise by the hybridization 
or crossing of two other species. The cross thus formed con- 
tained simply qualities that it had derived directly from its two 
parents, To prove however that the plants of fields and woods 
are producing purely fertilized seeds, of which one in every two 
or three hundred is capable of giving rise to an individual so dif- 
ferent from its ancestors as to constitute a new species is quite 
another matter, and cons t® the most important evolutionary 
discovery since the time of Darwin. Furthermore this newest 
aspect of the nee is of additional interest since the method of 
origin of species, one of the most elusive questions in the whole 
realm of natural history, has been brought within the range of 
experimental investigation, and has been so simplified that any 
one with a small garden at his command may, with patience, hope 
to make some substantial contribution to the subject. 
D. T. MacDoveat. 
