604 Validity of the Doctrine of Mutation. 
BRECHT and MORGAN have expressed themselves in favor 
of the new view, 1 the latter on the ground of his studies 
in the regeneration of injured organs. 2 
Amongst practical agriculturists my views have been 
well received by EM. VON PROSKOWETZ and HJALMAR 
NILSSON. The former has conducted a long series of in- 
vestigations on the transformation of the wild Beta patula 
into the sugar beet; and it was found that the changes 
do not by any means take place by imperceptible tran- 
sitions but suddenly. 3 Each new character is brought to 
light at one stroke ; it is not the product of selection but 
of internal processes, the nature of which we do not as 
yet know. Even such secondary characters as color, 
change in the same way. HJALMAR NILSSON, the direc- 
tor of the practical and experimental station for the im- 
provement of seed at Svalof in Sweden, has for many 
years been collecting a valuable mass of evidence, which 
promises to throw great light on the doctrine of muta- 
tion, but has not as yet, been grouped for that purpose. 
Judging from the oral and other communications which 
I have received from time to time from this investigator, 
I may state here that his results are in perfect harmony 
with the doctrine of mutation. 4 
ideallstische Richtung in der modernen Entivlckelungslehre, Zeitschr. 
f. Naturw., 1901, Vol. 73, p. 321. 
1 A. A. W. HUBRECHT, De cvolutie in nleuwe bancn, Utrecht, 1902. 
2 Tn. HUNT MORGAN, Darwinism in the Light of Modern Criti- 
cism, Harpers Monthly Magazine, Feb. 1903, and in many other 
papers. 
3 EM. v. PROSKOWETZ JR., CuUiirversuche mit Beta, 1892-1901 in 
Oesterr.-Ungar. Zeitschrift f. Zuckerindustrie und Landwirthschaft 
des Centralvereins f. Riibenznckerindustrie in d. Oest.-Ung. Mo- 
narchic, 1892-1902. The experiments of a given year will be found 
in the number for the following year, and in the number for 1892 will 
be found an account of the earlier experiments and the literature of 
the subject. For the mutations which occurred see especially the 
number for 1902. 
4 See the various numbers of the journal issued by the experi- 
