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VOLUME XXXVIII ; NUMBER 3 
BOTANICAL (GAZEERe 
SEPTEMBER, 1904 
THE DEVELOPMENT OF THE CENTRAL CYLINDER OF 
ARACEAE AND LILIACEAE. 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY. 
MINTIN ASBURY CHRYSLER. 
(WITH PLATES XII-XV) 
Tue fundamental unity of the vascular structures found in the 
higher plants was perceived by VANTIEGHEM, whose conception of 
the stele and its modifications, outlined in 1886 (17), displaced the 
earlier view of DeBary. But it became apparent subsequently that 
VANTIEGHEM’S assumptions were not sufficiently supported by 
observation. For example, it was shown by GWYNNE-VAUGHAN (3) 
that polystely does not arise by bifurcation of the protostele in the 
genus Primula, and JerrrEy (6) proved the same for_Pleris aquilina. 
VANTIEGHEM’s theory is also open to the objection that it is founded 
on the conditions occurring in a highly organized group of plants, 
while there would seem to be a better prospect of finding a primitive 
condition of the vascular system among pteridophytes. In 1897 
JEFFREY (5) proposed a stelar theory in which this objection is met, 
the essential feature of which is the important influence on the cen- 
tral cylinder of the outgoing leaf or branch traces. Emphasis is also 
Placed on the study of the young vascular axis, on account of its 
recognized importance in accordance with the principle of recapitu- 
lation. - The following diagrams may serve to show the main differ- 
ences between the two theories: 
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