484 BROOKLYN BOTANIC GARDEN MEMOIRS 



flowers and short spur branches were clustered at the extreme ends, 

 giving a pecuHar rosette-Hke appearance. The two types of fasciation 

 were quite distinct on the plant, both as to general appearance and 

 location. 



From the performance of these pedigreed cultures, it seems clear 

 that the character of duplication and cohesion persists in successive 

 generations of this variety of chicory to such an extent as to appear 

 strongly heritable. It is not completely so, for a few normal single- 

 stemmed plants do occur quite irregularly in various generations and 

 lines of descent. 



The heredity of the character of duplication has also been tested by 

 crossing plants of the 191 5 crop showing typical fasciation with a 

 plant of wild stock (plant A) which had a short, slender, main stem. 

 No tendency to duplication has been seen in plants of wild stock which 

 have been grown or in plants of various generations derived by crossing 

 the wild plant A with plants of the cultivated variety known as Barbe 

 de Capucin. This cross here in question involved, therefore, on one 

 side parents with duplication, and on the other a plant of a stock 

 free from duplication. 



Thus far 81 plants of an Fi generation have been grown; nineteen 

 of these had the wild plant yl as a seed parent. Of these 81 plants 

 only three possessed the grooves which are seen in most typical cases 

 of duplication of the main axis. In only one of these were the grooves 

 pronounced (see no. 10); in the other two there were only slight indi- 

 cations of grooves (see no. 11). In 78 plants there was not the slightest 

 indication by grooves of any duplication. However, in tracing the 

 phyllotaxy from base upward, irregularities were seen in 48 plants. 

 Two leaves or branches were often opposite or the direction of the 

 spiral would appear to shift from left to right or vice versa. In 30 

 plants the spiral of the phyllotaxy proceeded very regularly from base 

 to tip in a way that indicated a normal single stem-element (see no. 

 12). Of the 19 plants having the wild plant for a seed parent, 7 were 

 quite normal and in 12 there was a mixed or irregular phyllotaxy. 



Judged by performance in the Fi generation, the character of 

 duplication is only incompletely and partially dominant. An inter- 

 mediate type is frequent in which the only suggestion of a duplex con- 

 dition of the main axis is seen in an irregular phyllotaxy. 



I cannot at the present time contribute any information regarding 

 the sources, causes, or nature of the stimulus operating in duplication 

 nor any definite facts regarding the attending anatomical development. 

 When this paper was presented it was suggested by Dr. Erwin F. Smith 

 that possibly infection by some organism, bacterial or otherwise, was 

 necessary to the development of duplication as here observed. If this 



