the Sweet Potato. 213 
The two doubtful cases of ring-fasciation are: First, a 
“tubular stem of Sempervivum” recorded by Masters (12), 
and, second, two fasciated sweet-peas with “large tubular 
stems,” reported by C. P. Qualch (19) ; from inside the hollow 
of each of these arose a single stem, partly free and partly 
adherent. Probably all of these were cases of ring-fascia- 
tion. 
Concerning Michelis’ dandelions (14, 15), Nessler is doubt- 
less right in considering them as fusions, and belonging to 
quite another category. Neither can we get much light on 
the present subject from normal structures, as the fruits of 
Ficus or the “ hips”’ of roses, for in these the morphological 
apex of growth lies in the bottom of the cup-like body. The 
occurrence of two of the three true ring-fasciations in fasciated 
races, namely, Veronica longifolia and sweet potato, and the 
frequency of ring-fasciation and abundance of plain fascia- 
tion in the latter plant, make it highly probable that the 
two phenomena are but phases of one and the same con- 
dition. The very frequent splitting of the tubes into one 
to three or four bands makes the correctness of this view 
almost certain. An injury to the growing tip has been 
suggested as a cause of ring-fasciation, but no sign of such 
has been found in any of the cases examined. We may 
therefore consider that whereas plain fasciation occurs when 
the meristem is so stimulated (by overfeeding or otherwise) 
as to cause it to spread out in two opposite directions and 
become linear at the apex, ring-fasciation occurs when the 
same stimuli, operating for a time in radial symmetry, cause a 
spreading of the meristem in all directions equally, giving rise 
to a circular apical region.! 
Since going to press two ring-fasciated shoots have appeared on a plant of 
Symphytum caucasicum, growing in the University Botanic Garden. 
