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, I have 
here to add the following. 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. 1 TRACY has observed the sudden origin of 
a dwarf variety of Phaseohis lunatus, 2 MACFARLANE has 
investigated the variability in the genus Primus, 3 CARUEL 
has collected a number of cases in which direct transitions 
can be demonstrated and calls them "Euthymorphoses." 4 
CARLSON has investigated the mutations of the forms of 
Succisa occurring in Sweden, 5 and LAURENT expresses 
himself in the same way with regard to several species 
of fruit trees. 6 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- 
thamnus scoparius and Lupinus arboreus observed by 
him in New Zealand. It may further be mentioned that 
mental station at Svalof, Sveriges Utsddefdrenings Tidskrift, and 
particularly the Arsberdttelse under ar 1901, in Vol. XII, 1902, No. i, 
page 3. 
1 F. NOLL, Das Auftreten einer typischen Ranke an einer sonst 
rankcnlosen Pflansenart, Sitznngsber. d. Niederrhein. Ges. f. Naturk., 
Bonn, Jan. 14, 1895. 
2 W. W. TRACY, American Naturalist, 1895, XXIX, p. 485. 
3 J. M. MACFARLANE, Publications of the University of Pennsyl- 
vania, 1901, p. 216. 
4 T. CARUEL, Bull. Soc. Bot. Ital., Florence, 1896, p. 84. 
5 Bot. Not., 1901, p. 224. 
6 E. LAURENT, De I' experimentation en horticulture, 1902, p. 12. 
