Varietäten, Descendenz, Hybriden. 585 



4. This fact per se furnishes no evidence at all for the geno- 

 typic nature of the differences in Roemer's lines. Indeed, through- 

 out Roemer's work there is no conclusive evidence of any kind 

 concerning any problem of heredity. At least one (and possibly 

 both) of bis series of material is from bis own explicit Statements 

 in reality in pure line. The difference observed within these lines 

 and considered by him and other pure linists to be of genotypic 

 value and a confirmation ofjohannsen's results with beans are 

 probably merely the result of faulty experimental conditions. If 

 they are not, Roemer's evidence goes squarely against Johann- 

 sen's theory. Jongmans. 



Hus, H., The origin of species in nature. (The American 

 Naturalist. XLV. p. 641—667. 7 Fig. 1911.) 



This paper chiefly contains a review of literature on the origin 

 and discovery of new and aberrant forms. Many forms have been 

 discovered in gardens. Next to gardens, cultivated fields, i. e., 

 places v^rhere a large number of individuals of the same species or 

 variety are grown, offer the best opportunity for such discoveries. 

 The author discusses several white-flowering and white or yellow- 

 fruiting forms f. i. Solaniun Dulcamara, Medicago hybrids, Lobelia 

 cardinalis. 



Laciniate forms are of relatively frequent occurrence The writer 

 mentions such forms for instance from Algae, CaUophyllis fnvcata 

 dis&ecta, from Merciirialis, Chelidoniuni etc. 



The repeated sudden appearance of the same variety has been 

 noted by various authors. Thiselton Dyer was able to show the 

 repeated formation of at least two new varieties of Cyclamen 

 latifolium. 



A new form, which has appeared at various times and which 

 because of the nature of the Variation is incapacitated from repro- 

 ducing itself by seeds, would from this very fact constitute an ideal 

 Illustration of repeated mutation, since a hybrid origin of the 

 individuals which appeared later, is excluded. Such an instance is 

 yielded by Dianthus Caryophyllus imhricatus. Its sudden appearance 

 has been noted in different Stocks and at various times and places. 



Another interesting form is Arctiwn minus laciniaturn. It is a 

 question whether the plants of this form found at Albion are to 

 be considered as derived from preexisting plants of the variety or 

 whether they have arisen de novo. This form has been mentioned 

 several times since 1837 from different localities in the United 

 States, last time in 1910 from Albion. This form is of compara- 

 tively rare occurrence? From a glance at the accompanying map it 

 appears not improbable that this plant, perhaps having its origin in 

 Massachusetts, or introduced there from Europe, perhaps in 

 ballast, gradually has been transported to various points of the 

 compass, the area being covered by it being limited to the north- 

 eastern section of the United States. The transportation ofseed, 

 provided this is formed at all, is not unlikely. Fairly large gaps, 

 however, appear between certain of the dates of collection. So there 

 are gaps of eleven, fifteen and thirteen years. Yet these lacunae 

 very well may be accounted for by the failure ofbotanists to collect 

 and by the lack of data at our command. Jongmans. 



