Gates, Tetraploid Mutants ami Chromosome Mechanisms. |;>;' ( 



originally, self-pollinated yielded this year only three individuals, 

 of which two were typical lata and one Lamarckiana. 



It is hoped that this method of pollen examination will be 

 used in future by students of Oenot/tcrn, for it will evidently add 

 much to our knowledge of the constitution of the plant. 



Discussion. 



In this section it is first necessary to devote considerable space 

 to comments and criticisms of various statements made and concep- 

 tions held by other investigators. 



To begin the discussion, I must first complete the paragraph 

 from de Vries (1912, p. 34) from which the above sentence was 

 quoted, which is as follows: ,,Z\var hat Gates erne abweichende 

 Ansicht aufgestellt und behauptet, dass die Verdoppelung erst nach 

 der Befruchtung geschehen sein sollte, und nicht einer Mutation (sic), 

 sondern einem Zufall ('of the nature of an incident') zugeschrieben 

 werden miisste. Dieses wiirde den Vorgang in die Gruppe der er- 

 worbenen Eigenschaften (sic) uberfiihren. Und da man von diesen 

 jetzt wohl allgemein annimmt, dass sie nicht erblich sind, geniigt 

 die Vorstellung von vornherein nicht, um die Entstehung meiner 

 erblichen Rasse zu erklaren. Ich erinnere hier an die doppel- 

 kernigen Zellen von Spiroyym in den Versuchen von Gerassimow, 

 welche durch die vegetativen Teilungen hindurch ihre beiden Kerne 

 beibehalten, diese bei der Befruchtung aber wieder verlieren. 

 Ubrigens wird die Ansicht von Gates durch die neueren Tatsachen 

 vollig widerlegt." 



This passage requires several comments. I have already pointed 

 out that, so far from my view having been anomalous, it has been 

 supported by nearly all the cytologists who have had occasion to 

 deal with the subject. The second statement involves a miscon- 

 ception of my point of view. I have never suggested that the 

 origin of 0. gigas was not a mutation, but on the contrary, have 

 held it to be such, since it results from an inherited germinal 

 change. I have, however, held it to be phylogenetically "of the 

 nature of an incident", and in this it probably agrees with many 

 other mutations, though it is, of course, almost impossible to 

 measure the phylogenetic value of any germinal change when it is 

 viewed in such short perspective. The numerous cases of tetraploid 

 species among plants, and less frequently among animals, show, 

 however, that this condition is, as I have pointed out (1909 a), of 

 great evolutionary interest. 



The next statement of de Vries, that the origin of gigas from 

 a change occurring in the fertilized egg, or in the megaspore mother 

 cell would place it in the category of "inheritance of acquired 



