1906] _ CURRENT LITERATURE 357 
Neckeraceae.—U. DamMeErR (Notizblatt Kénig. Bot. Gart. 4:171-173. 1905 
describes a new genus (Kinetostigma) of Guatemalan palms.—E. JANcZEWSKI 
(Bull. Acad. Sci. Cracovie, pp. 13. Jan. 1906), in his second paper on Ribes, 
presents the species of the subgenera Ribesia and Coreosma, including new Cali- 
fornian and Mexican species.—A. Borzr (Notarisia 21: 14-16. 1906) describes a 
new genus (Zoddaea) of Chlorophyceae (Chroolepidaceae) from a Mediterranean 
island. 
Heredity.—A lecture on heredity and the origin of species by MAcDoucaL? 
not only presents the author’s views regarding the several more prominent 
evolution hypotheses, but also makes the first public announcement of impor- 
tant results of his own researches on the causes of mutatio 
While not denying the possibility of other means of peodiicticns of species, 
he holds that hybridization and mutation are the only demonstrated methods 
by which new species have arisen. He attributes a popular belief in the Neo- 
Lamarckian hypothesis to the supposed effects of garden practice, and these 
supposed effects are supposed to be due to the prevalence of vicinism and the 
vegetative propagation of bud-sports. Several ‘unsurmountable objections” 
are opposed to the Neo-Darwinian hypothesis of natural selection of slight varia- 
tions as a universal method. He would distinguish orthogenesis from deter- 
minate variations, limiting the former to an internal perfecting force which 
evolves rudimentary organs and develops them to ieangs structures without 
any reference to selection; while the latter he would allow as a part of every 
method of evolutionary procedure, in that no structure may vary to any other 
Structure too much unlike itself. This is a very important discrimination theo- 
retically, but it is clear that in most cases a practical distinction between ortho- 
genesis and determinate variation as here defined would be an impossibility, 
since the “morphological possibilities” may be estimated only by what does 
appear. 
The effects of isolation and of self- and cross-fertilization are held ix 
be problematical. 
€ greater part of the lecture is naturally devoted to the mutation cultures 
of DE Vries and himself. Besides Oenothera Lamarckiana, the "following three 
species have been shown to be in a state of mutation: O. grandiflora, O. bien- 
nis, and O. cruciata. ‘Parallel mutations’’ are exemplified by two observed 
origins of nanella-forms, i. e., forms with linear petals. A consideration of the 
mutating and mutant species leads to the conclusion that plants are made up 
of complex groups of unit characters, that some of these characters may exist 
for an indefinite time in a latent state, that anew character that departs widely 
from the parental condition is more variable than the homologous character 
of the parent species, and that at the same time it is less closely correlated. 
'? MacDoveat, D. T., Heredity and the origin of species. Lecture given before 
the Barnard Botanical Club, Columbia University, ae 18, 1905. The Monist, 
Jan. 1906. 32 pages. Printed and distributed in advan 
