420 EXPEBI31ENTS WITH PLANTS 



The variations just discussed are the ordinary 

 Idnd and may be called fluctuating variations (because 

 they fluctuate around a mean, or average type) to 

 distinguish them from sudden variations or sports 

 (e. g., reversions and monstrosities), which are sudden 

 and apparently lawless deviations from the type and 

 only occur occasionally; fluctuating variations, on the 

 otlier hand, occur everywhere and in all plants. A 

 Peach tree occasionally produces a branch which 

 bears only nectarines; this is called a sport. If the 

 branch be cut off and used as a cutting it will produce 

 a Nectarine tree. Occasionally a Ijranch of this may 

 produce peaches: this return to the original condition 

 is termed atavism, or reversion, and is also apt to occur 

 in plants which are not known to have originated 

 as sports. When a sudden variation originates, as 

 in this instance, from a single l)ud on a plant, it is 

 called a "bud -variation." The various Moss Roses, 

 many kinds of Chrysanthemums, many variegated 

 plants, etc.,^ have originated in this way. The word 

 sport is usually applied to bud- variations, but is 

 not necessarily limited to them. It may be used for 

 any kind of sudden variation. .The term monstrosity is 

 commonly used to designate a sudden variation which 

 has the appeai-ance of an abnormality or deformity; 

 as, for example, when a stem becomes flattened and 



'Sec Bidley: "Plniil Bi-eedins," first edition (IHliril or second eilitioii 

 (1902), Lecture IV. (This lecture does not apjiear in the third edition, 

 1904.) 



