6oo 
Notes . 
As far as the investigation has gone, the primitive scattered arrange- 
ment of bundles can be traced in the stem of about thirty dicotyle- 
donous orders, viz., Ranunculaceae, Nymphaeaceae, Berberidaceae, 
Calycanthaceae, Magnoliaceae, Anonaceae, Cruciferae, Fumariaceae, 
Papaveraceae, Geraniaceae, Umbelliferae, Compositae, Plumbaginaceae, 
Acanthaceae, Campanulaceae, Solanaceae, Cucurbitaceae, Begoniaceae, 
Polygonaceae, Amaranthaceae, Chenopodiaceae, Nyctaginaceae, Phyto- 
laccaceae, Melastomaceae, Cactaceae, Ficoideae, Orobanchaceae, Pipera- 
ceae, Balanophoraceae, Araliaceae, and no doubt many more will 
reveal it. 
Other characters very frequently accompanying the above feature in 
dicotyledonous stems are : — 
(a) V-shaped xylem ; (5) reticulate and circular phloem ; (<r) bundle 
often concentric, with central circular phloem, and when collateral 
often with irregular orientation ; (d) few, large vessels in xylem ; (e) 
bundle rounded or elliptic and enclosed in sclerotic sheath ; (/) very 
small development of cambium ; (g) largest bundles occur nearest 
centre of stem, the smallest nearest the periphery; (k) rudimentary 
character of many bundles, representing those members of the vanishing 
scattered system which are not destined to form part of the functional 
cylinder ; ( i ) limit between cortex and cylinder marked by a sclerotic 
zone; (J) cortical system of bundles which are often concentric in 
structure ; (k) trimerous character of some or all of the floral whorls ; 
(/) several orders exhibit 5 -merous single perianth-whorl in flowers, 
which, as Celakovskf has shown, is derived from two trimerous whorls 
by conversion of lowermost perianth-member into a bract. 
In some Monocotyledons the scattered bundles have become very 
peripheral, and even reduced to a single series or row of bundles. 
In some cases amongst Dicotyledons where the scattered arrange- 
ment has vanished from the stem it can still be found in the less modi- 
fied foliage-leaf, especially where the petiole is cylindric in contour or 
possesses a considerable diameter. 
In view of the above facts the author cannot agree with those writers 
who maintain that the vascular structure of the seedling stem of 
Dicotyledons generally proves it to be primitively tubular in character. 
The same will, for reasons above set forth, apply to the case of Mono- 
cotyledons. 
Kew, 
W. C. WORSDELL. 
