Studies of Teratological Phenomena. 



59 



A more detailed account of the linear type as it occurs in Nicotiana 



is given under "materials" in the part devoted to a special study of 



Nicotiana tahacum faseiata. Often the main stem is the only organ 



altered, and the degree of this alteration in plants of the same pure 



line^) may vary from a perfectly normal to an extremely abnormal 



condition. De Vries states this variability to be true of all of his 



"eversporting" fasciated races. "Ring" and „linear" are the two main 



morphological types, but probably 



"witch-brooms" should also be 



classed as a form. Very generally 



(and this is true especially of 



fasciation in woody plants) the 



surface of the stem is striated by 



the prominence of woody fibers 



(Fig. 3). Fasciated branches or 



main stems, owing to more rapid 



growth on one side than on the 



other, are not infrequently curved, 



presenting an appearance that may 



be likened to a shepherd's crook. 



Branches. Branches may 

 remain unfasciated, even though 

 it is expressed in the main axis. 

 In Pisurn and Ruhus, both are 

 altered; in Nicotiana, egnerally 

 only the latter. In cases represen- 

 ting Godron's fourth class, a 

 small branch may be the only 

 part of the plant affected. Examples 

 of this kind are common in trees 

 and large shrubs. 



Leaves. Leaves are usually modified by the presence of fas- 

 ciation only through their relation to the main axis. Changes in number 

 and position are common, changes in size and shape uncommon. 

 Alterations in number and position are exceedingly irregular in character 



(a) (h) 



Fig. 3. 



(a) Fasciated branch of Acer rubrum. 



(b) Fasciated stem of Erigeron canadensis. 



^) The term "pure line" as used in this paper refers to the descendants of a 

 single self-fertilized ancestral plant, and does not refer in any way to the degree of 

 homozygosity of this descendant population. 



