i9 14] BRANNON—FASCIATION 521 



had been moving freely through the tissues of the tree while it 

 was standing. There might have been larger quantities of various 

 chemical substances per unit of living tissue, but hardly a different 

 quality than that present in the uncut cottonwoods and willows. 

 The soil had not been disturbed; there had been no change in 

 drainage, and no great variation of precipitation during the latter 

 months when the trees were standing and during the time that the 

 fasciated sprouts had been developed. This seemed to indicate 

 that, so far as the causes of fasciation in the stems of cottonwood 

 and willow were concerned, it was necessary to seek them among 

 physical rather than among chemical factors. From the list of 

 physical factors such as light, gravity, and turgor it was easily 

 possible to select turgor as the one which would be variable in the 

 meristematic tissue near the exposed surface of the tree stumps 

 out of which numerous sprouts developed. Root pressure of the 

 cottonwood and willow plants was apparently in full operation 



months 



meristematic 



stumps from which a few buds developed in the early spring 

 > seemed the Drobable cause in the production of the ohenom 



willow 



Traumatism 



in the young, rapidly growing sprouts. However, this seemed 

 improbable, inasmuch as numerous sprouts were wholly free 

 from fasciation, notwithstanding the fact that some of the more 



normal 



fasciated sprouts came from the same 



snrouts were ff rowing.. Transition from 



mally fasciated to the normal radial symmetry was evidenced by 

 the most strongly fasciated sprouts after three seasons of growth. 

 Figs. 5 and 6 show the bases of cottonwood saplings which had 

 sprouted from the stumps four years before. The wide scar near 

 the base of each fasciated specimen clearly indicated the location 

 of a ruptured cortex which took place in the deeply furrowed 

 fasciated specimen during its second season's growth. The 

 dimensions of the cross-section of the base of the specimen shown 

 * n %• 5 were 6 by 4.5 cm. Fig. 6 shows the base of a fasciated 

 stem whose cross-section is cm. from the ground was 6. z bv S cm. 



