604 Validity of the Doctrine of Mutation. 



BRECHT and ]\IoRGAN havc expressed themselves in favor 

 of the new view,^ the latter on the ground of his studies 

 in the regeneration of injured organs.^ 



Amongst practical agriculturists my views have heen 

 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 imperceptil^le tran- 

 sitions but suddenly.^ 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 w^e 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 tlie 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.'* 



tdcalisfischc Richfting in dcr modcrnen Enfzvichelungslehrc, Zeitschr. 

 f. Naturvv., 1901, Vol. 73, p. 321. 



^ A. A. W. HuBRECHT^ De evolutie in niciiwe hancn, Utrecht, 1902. 



*Th. Hunt Morgan, Danvinism in the Light of Modern Criti- 

 cism, Harpers IMonthly Magazine, Feb. 1903, and in many other 

 papers. 



^ Em. v. Proskowetz Jr.. Culturrersuche mit Beta, 1892-1901 in 

 Oesterr.-Ungar. Zeitschrift f. Zuckerindustrie und Landwirthschaft 

 des Centralvereins f. Riibenzuckerindustrie in d. Oest.-Ung. ]\Io- 

 narchie, 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. 



* See the various numbers of the journal issued by the experi- 



