JOURNAL 
The New York Botanical Garden 
Vou. VI. Febuary, 1905, “No. 62, 
STUDIES IN ORGANIC EVOLUTION. 
Soon after the appearance of the first volume of Professor 
deVries’s book on the “ Mutation Theory of Organic Evolution " 
the author began a series of cultural tests of Lamarck’s evening- 
primrose and some of the ‘‘ mutants” which had arisen from it 
in order to ascertain whether these “ seed-sports’’ or mutants 
were stable, and what relation they bore to their parent. By a 
series of extensive cultures begun in 1884 Professor deVries had 
found that pure strains of this plant produced seeds, some o 
which gave rise to forms which in their structure, habit and ao 
progeny were quite unlike the aera type. These ‘ mutants’ 
constituted one to five per cent. of the entire progen wide 
range of similar occurrences were also observed in se: plants. 
This discontinuity or break in descent, by which new qualities 
arise suddenly, or disappear at once constitutes the basis of the 
mutation, or saltation theory of evolu 
The results of the earlier tests were ‘published in the American 
Naturalist for November, 1903. The investigations upon the 
group of plants mentioned above has widened until more than 
120 different cases, or experimental cultures, are under observation 
in addition to experiments on heredity with other species which 
have been under way. in the New York Botanical Garden for a 
much longer time. 
Attention is being devoted to the determination of the actual 
composition of the various species, to an analysis of the genetic 
