454 
Hill and de Fraine>—On the 
Bowenia. 
Bowenia spectabilis . Our knowledge of the seedling structure of this 
plant is due to the work of Pearson, 1 who gives an extended description of 
the morphology and structure of the plant in question. Each cotyledon 
contains from four to seven vascular bundles, the neighbouring ones of which 
may fuse together so that four strands enter the hypocotyledonary axis 
from each seed-leaf. These, in the axis, join together, and with the traces 
derived from the plumule form a concentric pithless vascular cylinder, the 
centre of which is occupied by protoxylem elements. From this central 
strand there is quickly organized a diarch root-structure which becomes 
triarch at a slightly lower level, which arrangement in turn gives place 
to a pentarch root-structure which persists for some distance downwards. 
Whether, in older seedlings, this pentarch organization becomes reduced to 
a diarch structure, such as Matte found to obtain in Stangeria and Cerato - 
zamia , Pearson does not state. 
From Pearson’s account it appears that the transition-phenomena 
in Bowenia spectabilis are of the same type as generally obtain in 
Macrozamia spiralis . 
Zamia. 
As far as has been seen there exists no account of the seedling- 
structure of species of this genus of any importance in the present con- 
nexion. Van Tieghem 2 states that in Zamia furfuracea the number 
of cotyledons are usually two, but sometimes one and sometimes three 
obtain. In dicotyledonous examples each seed-leaf has four vascular 
bundles ; in the monocotyledonous specimen there were eight cotyledonary 
strands ; and, finally, in the tricotyledonous plant, each seed-leaf had two 
vascular bundles. A cotyledonary tube commonly is formed, and the root- 
structure is tetrarch. 
Zamia spiralis sometimes has the tips of the cotyledons lobed to such 
a degree as to suggest a pinnate lamina 3 ; a fact which has also been 
observed by Miss Dorety, 4 who states that species of Zamia have seed- 
leaves with four to ten lobes, and that the transition is of the same type as 
in Dio on edule. 
Summary. 
Cotyledons. 
1. In all the plants examined the seed-leaves are hypogeal, and are 
embedded in the prothallus throughout their existence. 
2. They are very generally two in number ; three have been observed 
in Ginkgo bilob a. 
1 Pearson: Anatomy of the Seedling of Bowenia spectabilis (Ann. Bot., xii, 1898). 
2 loc. cit. 3 Sachs: Text Book, 2nd Ed., p. 501 (Oxford, 1882). 4 loc. cit., 1909. 
