1902] CURRENT LITERATURE 237 
the other hand, brings into existence something altogether new, the mutant 
remains fixed from the outset, and if it is fit, it will survive the struggle for 
existence as a new species. Mutability and variability are sharply con- 
trasted; variability is obviously governed by external factors, especially 
autrition, while mutability has no such obvious connection. Thus we may 
say that most species are fixed and immutable, yet more or less variable from 
their origin to their final extinction. 
De Vries accepts Jordan’s idea of species, viz., that within the Linnean 
Species there may be ‘‘elementary species” (varieties, of authors), which are 
aecinaeaaed immutable. Jordan found about 200 immutable forms within 
the ordinary species limits of Draba verna,; hence the idea that Draba verna 
is a collective group, and that the 200 immutable forms represent true 
Species. In such cases the author favors a trinomial nomenclature. 
Of a number of natural species studied, Oenotheru Lamarckiana was the 
only one which appeared to be in a state of mutability. This species was 
found naturalized on a field near Hilversum, Holland, about 1875, and has 
increased its area rapidly. When first observed by De Vries in 1886, two 
tary Species were noticed among the normal forms, and were named 
c. author Ocnothera brevistylis and laevifolia. Since that time these 
Pa a maintained themselves, in spite of hybridization and the struggle 
: ence. From 1886 until now De Vries me anne observations | in oe 
feld at Hilversum, and has made almost i 
a 
-_— 
- me, eperinenta results may be briefly summarized. Out of 50,000 
> b tre of Oeno Lamarckiana in the various years of study, 800 or — 
of | eae were mutants, while 98.5 per cent. came true to seed. 
not only in one but in several characters. 
a n an exhaustive and satisfactory fashion that his new forms 
identify rckiana, muricata, cruciata, etc.). ; pe 
4 ¥ most of the species with certainty, as early as the rosette 
Species having round and others grasslike leaves. ‘The ‘muta- - 
(Occurring in all possible directions, involving all - 
her outset ; there is no fixation of their ch 
d is there si reversion. There are no transitions | 
eae ie ‘One Sexo! interesting result is. that lend mutan' 
* 800 ‘iss oo aoond than one fourth —— to the new i - : oe 
