Seedling Structure of Gymno sperms. I. 709 
The transition is the same as in Sequoia gigantea ; a diarch root is, 
however, always formed. 
It may also be remarked that the same variations in the phase of 
transition of the cotyledonary bundles at the same level occur in this plant 
as have already been described above for species of Juniperus , Cupressus, 
Cal litr is, and Sequoia. This is illustrated by Figs 14 and 15, Plate XXXV. 
SUMMARY AND CONCLUSIONS. 
Cotyledons. 
1. As regards the number of cotyledons, the following plants have two 
Taxus , Cephalotaxus , Podocarpus , Juniperus, Cupressus obtusa , C. Law - 
soniana , C. pisifera , Thuja , Ac linos trobus, Callitris , Widdringtonia , 
Sequoia sempervirens , and Sciadopitys. 
The following have 2-3 : — Libocedrus decurrens and Cryptomeria 
japonica. 
The following have 3-4 : — Cupressus macrocarpa and Sequoia gigantea. 
The following has 'g-g.-— Cupressus tondosa. 
2. Some of the poiycotyledonous seedlings form a short cotyledonary 
tube by the lateral union of the seed-leaves in the proximal region, e. g. 
Cupressus torulosa. Occasionally the two seed-leaves fuse laterally to form 
a single member, e.g. Widdringtonia Whytei. 
3. Resin ducts, as far as has been seen, are absent in the seed-leaves of 
Cephalotaxus , Taxus , Podocarpus , Juniperus , Cupressus , Libocedrus , Thuja , 
A clinos trobus, Callitris, and Widdringto?iia. They are present in the 
cotyledons of Cryptomeria, Sequoia, and Sciadopitys. 
4. With the exception of Podocarpus and Cupressus tondosa , the seed- 
leaves each contain a single vascular strand. 
Podocarpus has two bundles, entirely separate, in each cotyledon, and the 
same may occur in Cupressus tondosa, which is due, in this particular 
plant, to the splitting of certain of the seed-leaves. 
5. The cotyledon-bundles have a pronounced mesarch structure in 
Cephalotaxus ; the phenomenon is much less obvious in Taxus and Juni- 
perus ; and is merely indicated by one or two centripetal xylem elements in 
Ctipressus obtusa, C. macrocarpa, and Callitris . 
6. Transfusion tracheides are generally present. 
7. Elements of a fibrous nature occur in the bast of Cephalotaxus, Taxus, 
and Thuja. 
Transition-phenomena. 
8. The transition of the majority of the Taxaceae and Cupressineae 
follows Van Tieghem’s Type 3. That is to say, the single vascular strand 
of each seed-leaf undergoes bifurcation of the vascular tissues accompanied 
