608 TRANSACTIONS OF THE CANADIAN INSTITUTE. - [VoL, VI. 
cotyledons, and then bifurcates, repeatedly producing a varying number 
of eccentric steles." The fibro-vascular system in this case is 
described as polystelic Van Tieghem retains, for species possessing a 
cauline central cylinder of the first type, the original Linnean generic 
name Primula; for the polystelic species, he revives Tournefort’s genus 
Auricula. 
Van Tieghem does not seem to have followed closely the develop- 
ment of the polystelic type in his genus Auricula. The writer has given 
some attention to this subject, but it has not seemed necessary to make 
his studies exhaustive, because an admirable account” of the whole 
matter has recently appeared, with which the writer’s own results are in 
~ close agreement. Gwynne-Vaughan has examined the development of 
the young stem and the relation of the leaf-traces to the cauline central 
cylinder. He calls attention to the fact that the young pithless stele of 
P. japonica and P. involucrata after the exit of from four to 
eight leaf-traces becomes gamodesmic (gamomeristelic) in the same 
manner as the central cylinder of the young stem of Botrychium 
Lunarta, described by Van Tieghem. In other words, there is present 
a collateral fibro-vascular cylinder with an internal endodermis as well 
as an external one. This cylinder is perforated at intervals by the gaps 
occurring at the points of exit of the leaf-traces, and around the margins 
of these gaps the external and internal endodermis become continuous. 
Higher up in the young stem, the gamodesmic cylinder becomes more 
or less completely gamostelic by the formation of internal xylem and 
phloém. The leaf-traces show the same variability as the cauline 
strands. In the petioles of the younger leaves they are collateral 
strands, while in the stalks of the later-formed foliar organs some of 
them become concentric and would thus be considered, from Van 
Tieghem’s standpoint, as steles. 
As regards the nature of Polystely itself, this writer reaches conclu- 
sions which are so much in accord as far as they go with the investiga- 
tions to be described in this memoir, that they may be quoted in full. 
For example (p. 320) he makes the following statement: “Van Tieg- 
hem seems to have entirely overlooked the all-important influence of 
the leaf-traces on the phenomena of transition, and, indeed, on the vas- 
cular system throughout the whole plant. On this account, he regards 
Polystely, when present, as having originated by the continued bifurca- 
tion of the central cylinder found in the lower part of the stem. He 
speaks of it as flattening itself out, and constricting itself in the middle 
21. Op. Cit., p. 305. . 
22. Gwynne-Vaughan ; Polystely and the Genus Primula, Ann. Bot., 1897. 
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