567 
Yoitng Plant of Macrozamia Fraseri. 
by Marsh. 1 These being found insufficient to elucidate the finer details of 
structure, serial sections were then prepared on the Jung microtome, some- 
times with the aid of a freezing apparatus. It was, however, still found 
impossible to elucidate some points in the anatomy, owing to the exceeding 
complication of the structure, and the absence, which these methods entail, 
of any good system of orientating the series. Finally, the plants were 
divided up, and their successive portions embedded in paraffin. This 
method proved very successful if sufficient time — about a month — were 
allowed for penetration. By the use of the Minot microtome longitudinal 
and transverse serial sections of practically every portion of the plant were 
thus obtained. Staining was generally done upon the slide, and gentian 
violet and Bismarck brown was the most usual combination used. In some 
cases, for coarse details of structure, the staining was done under wax with 
eosin. 
I. Seed and Seedling. 
The seeds — 3.5 cm. long and 2-5 cm. broad — contain embryos with 
closely adpressed, partially fused, hypogeal cotyledons of unequal length, the 
petioles forming below a cotyledonary tube. 
On germination, disorganized coleorhiza, root, and lastly plumule 
emerge in the sequence given, and in the manner described for other Cyca- 
dean seedlings. 2 As the plumular axis grows, and the base of the first 
plumular leaf rapidly expands, the size of the opening in the cotyledonary 
tube by which the plumule is emerging is actively increased, on the side ad- 
jacent to the leaf midrib, by the action of a phellogen ; this cuts off from 
the side of each cotyledonary petiole successive layers of cells, which 
become disorganized, and so give the plumular axis room to emerge 
and expand. 
Anatomy : (a) Mucilage canals. Each cotyledon is traversed by two 
roughly parallel rows^ of mucilage canals — the one row within, and the other 
outside, the row of vascular bundles. These are reduced in the petiole, by 
anastomoses firstly between the canals of a row, and next between those of 
outer and inner rows, to a series of about five ducts, which alternate with the 
leaf-traces. New canals may arise lysigenously at any point in the cotyle- 
don. Tannin-containing cells are numerous in the lower portion of the 
cotyledon, though absent from its apex. These occur in or immediately 
beneath the epidermal layer. 
( b ) Vascular system. The cotyledons show that parallel dichotomizing 
venation characteristic of Cycadean seedlings. In this species six mesarch 
traces occur, as a rule, in the middle region of the cotyledon — reducing 
1 Marsh : Notes on the Anatomy of Stangeria paradoxa. New Phyt., vol. xiii, Nos. i and 2, 
I 9 I 4* 
2 Dorety : The Seedling of Ceratozamia. Bot. Gazette, vol. xlvi, 1908, p. 46. 
