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THE AMERICAN NATURALIST [Vol. XLV 



since the addition of such an exceedingly variable char- 

 acter as is pubescence, seems sufficient to bring this about 

 (Solanum Dulcamara var. villosissimum Desv.)? 



The last illustration points to the largest source of 

 new or at least imperfectly known species and varieties, 

 i. e., the native flora. The same rule applies here as in 

 cultivated fields : striking morphological differences most 

 readily attract attention. When the plant normally is 

 possessed of large leaves, as is, for instance, Arctium 

 minus, any differences in the foliage become especially 

 noticeable. It is through this fortunate circumstance 

 that we owe to Professor Charles E. Barr, of Albion 

 College, Michigan, the discovery of at least a new local- 

 ity for the apparently rare laciniate form of the species 

 just mentioned (Fig. 3). 



Laciniate forms are of relatively frequent occurrence. 

 We find them not only among the phanerogams and the 

 vascular cryptogams, but even among the algae one can 

 meet with forms which may be interpreted as such, for 

 instance Callophyllis furcata Farlow 35 and C. furcata f. 

 dissecta Farlow 86 (Fig. 4), though of course there is no 

 connection. One of the earliest accounts of the sudden 

 appearance of a laciniate variety is given by Marchant. 37 

 In 1715, in his garden, he discovered a plant which, 

 though evidently belonging to the genus Mercurialis, was 

 entirely new to him and which did not appear to have 

 been described previously. He named it Mercurialis 

 foliis capillaceis. No seed being collected, the next year 

 the same garden spot was anxiously watched. Six plants 

 made their appearance, four of which possessed the 

 character of the plants which had appeared in 1715. 

 The other two were sufficiently different to be segre- 



"Exsic. in Collins, Holden and Setchell, Phycotheea Bor. Am. Fasc. 38, 



»Setchell, W. A., and Gardner, N. L., "Alga; of Northwestern Amer- 

 ica," 306, Univ. Calif. Publ., 1, 1903. 



"Marchant, J., "Sur la production de nouvelles especes de plantes," 

 Hist, de I'Acad. d. Sc., 1719, 57, Paris, 1721. 



Marchant, J., "Observations sur la nature des plantes," Mem. de 

 I'Acad. Boy. d. Sc., 1719, 59, pi. 6, 7, Paris, 1721. See also The Amkrican 



