In this discussion we are concerned primarily with the types of bud variations 

 which are inherited. These types may be conveniently divided into two classes, 

 (a) bud fluctuations or continuous bud variations and (b) bud mutations or dis- 

 continuous bud variations. Castle defines fluctuations as "those which are purely 

 quantitative, plus or minus, as compared with the prevailing racial condition" (10). 

 The value of bud fluctuation or continuous bud variations in the work of plant 

 improvement is a matter of dispute amongst some investigators. The particular 

 point at issue seems to be the possibility of changing the mode or increasing the 

 maximum through the continuous selection of maximum bud fluctuations. The 

 experience and observations of the writer have led him to believe that by con- 

 tinuous selection in isolated strains the mean of the variation in the selected popu- 

 lation may be raised to a point more nearly approximating the maximum exhibi- 

 tion of the character in the strain. This conclusion has been reached as the 

 result of study and observations in the amelioration of several of our important 

 economic plants, among which may be mentioned the increase of the average 

 percentage of oil, protein, and starch in the composition of maize through the 

 systematic selection of seed possessing the maximum amounts of these elements 

 in their composition ; the increase in the yield of varieties of tobacco through the 

 systematic selection of seed from the best individual plants ; the increase in yield 

 of violets through the selection and propagation of cuttings from the most pro- 

 ductive plants ; the increase in the yield of potatoes by the selection of tubers from 

 the high-yielding hills ; the improvement in the yield of citrus fruits through the 

 propagation of the best-yielding parent trees ; and many other equally striking 

 similar experiences. It is argued by some of the opponents to this conclusion 

 that even if these improvements in plant behavior have been effected it will be 

 necessary to continue the selection by means of which they were secured in order 

 to preserve and maintain them. This idea may or may not be correct, and even 

 granting that it may be sound in some cases, it does not vitiate the fundamental 

 importance of selection in developing and maintaining improved production. It 

 is the personal opinion of the writer that through the selection of observed bud 

 fluctuations in any plant character, such as size, number, or chemical composi- 

 tion, those of genetic character will be included so that through repeated selec- 

 tion races will be developed which are progressively larger, more productive, or 

 otherwise changed in the direction of the selection. From the commercial stand- 

 point it is thought that this phase of plant breeding is the most important one 

 concerned in the work for the improvement of plants. 



The terms bud mutations or discontinuous bud variations in this discussion 

 will be used to define sudden or marked variations from the parental forms in 

 vegetatively propagated plants. Darwin called such variations bud sports, but 

 this term has been largely superseded by the term bud mutation as proposed by 

 De Vries. Many of our valuable varieties and strains of cultivated plants have 

 originated from bud mutations. It is probable that amongst vegetatively propa- 

 gated plants a majority of the important commercial varieties have originated in 

 this way. In seed propagated plants, it is the writer's conviction that a consid- 



