140 



THE AMERICAN NATURALIST 



[Vol. LI 



where new characters arise ; retrogressive, where a char- 

 acter becomes latent or lost ; and degressive, where latent 

 characters become active. In this important monograph 

 practically all recorded bud-variations to the date of pub- 

 lication, 1907, are discussed. Yet not a single case of 

 progressive variation is listed. They are all catalogued 

 as retrogressive or degressive. Their classification is 

 correct, however, only when a progressive variation is 

 defined as the addition of a character wholly unknown in 

 the previous history of the species. 



As examples of what bud-variation does produce we 

 may well study Cramer's painstaking work. There are 

 losses of thorns, hairs and other epidermal characters, 

 together with an occasional degressive change of the 

 same kind. There are changes in color in vegetative 

 parts. Green becomes red or ''aurea" yellow, or a loss 

 of anthocyan occurs. Sometimes the changes are such 

 that the plants remain striped or otherwise variegated. 

 Flowers and fruits exhibit the same types of color varia- 

 tions in considerable numbers. They are mostly losses, 

 with the appearance of what in Mendelian terminology 

 is called hypostatic colors, but once in a great while 

 epistatic colors recur anew. 



Monstrosities appear. Other parts of the flower take 

 on the appearance and form of petals or of sepals. Dou- 

 bling occurs in several different ways. Fasciations arise. 

 Changes in the character of the reproductive apparatus 

 are not uncommon, sometimes giving us seedless fruits. 



Plants change their habit of growth. They become 

 dwarf. They retain juvenile characters. They become 

 laciniate, or develop the trait known as "weeping." 



Thus we see that bud-variation is not limited in its 

 manifestations; and what is more important, we realize 

 that bud- variations are very comparable to seminal varia- 

 tions, there being hardly a type of change 

 sexually reproduced plants that has not been du] 

 asexually. What then is the difference, if any, 

 true somatic changes and true germinal changes 

 stitution? We can get clues which indicate 



