Significance of the Available Evidence. 605 



To the important observations already mentioned, 

 made by Heinricher on Iris pallida abavia, by Solms- 

 Laubach on Capsella, by Wittrock on Viola, by Bailey 

 and White on Tomatoes, and by many others, 1 have 

 here to add the follov^ing. Noll has described the sud- 

 den origin of a regular tendril in Tropaeolum, and draws 

 conclusions from this in favor of the possibility of dis- 

 continuous changes and their significance for the theory 

 of descent.^ Tracy has observed the sudden origin of 

 a dwarf variety of Phaseolus lunatiis,^ Macfarlane has 

 investigated the variability in the genus Primus,^ Caruel 

 has collected a number of cases in which direct transitions 

 can be demonstrated and calls them ''Euthymorphoses.""* 

 Carlson has investigated the mutations of the forms of 

 Succisa occurring in Sweden,'"^ and Laurent expresses 

 himself in the same way with regard to several species 

 of fruit trees. ^ Dr. J. W. Harshberger sent me mate- 

 rial of Hibiscus moscheutos and Euphorbia ipecacuanha 

 from Pennsylvania, the extraordinary abundance of forms 

 in which seems to indicate the occurrence of a period of 

 mutation in these species ; and Mr. L. Cockayne has 

 given me information on some transformations of Saro- 

 thammis scoparius and Lupinus arboreus observed by 

 him in New Zealand. It may further be mentioned that 



mental station at Svalof, Sverigcs Utsddcfdrcnint^s Tidskrift, and 

 particularly the Arsberdttelse under ar 1901. in Vol. XII. 1902, No. i, 

 page 3. 



^ F. Noll, Das Auftrctcn cincr typischcn Ranhc an ciucr sottst 

 rankcnlosen PHanzenart, Sitzungsber. d. Niederrhcin. Ges. f. Naturk., 

 Bonn, Jan. 14, 1895. 



^ W. W. Tracy, American Naturalist, 1895, XXTX. p. 4S5. 



' J. M. Macfarlane, Publications of the University of Pennsyl- 

 vania, 1901, p. 216. 



' T. Caruel, Bull Soc. Bot. Ital, Florence, 1896, p. 84. 



^ Bot. Not., 1901, p. 224. 



"E. Laurent, De I' experimentation en horticulture, 1902, p. 12. 



