594 7 e ff re y • — Trcttcmaiic Ray-Tracheids in 
consequent modernity. This complexity of organization is found also in 
the reproductive organs of the group. Penhallow has called attention, 
however (Anatomy of North American Coniferales, American Naturalist, 
vol. xxxviii, p. 341, 1904), to the presence of the characteristic marginal ray- 
tracheids oftheAbietineae in the Cupressineous genera, Juniperus, Cupressits , 
and Thuya. They occur in the following species in a sporadic and uncertain 
manner, Juniperus nana , Cupressus thuyoides , and C. nootkatensis , and in 
Thuya jap onica. They are also found in certain of the Taxoidineae. In 
his Comparative Anatomy (Eng. Trans., p. 490) De Bary describes their 
presence in the monotypic genus Sciadopitys. More recently Gothan 
(Just Jarhresberichte, vol. 31, p. 848), in a review of a work by the present 
author on the genus Sequoia , mentions the sporadic occurrence of marginal 
tracheids in the old wood of Sequoia gigantea . Finally the writer has 
observed the presence of marginal tracheids in the wood of Cunninghamia 
sinensis , under conditions to be described below. It will appear from the 
above that both in those genera which at present it is customary to include 
under the Cupressineae, and in those which are united under the Taxodineae, 
there are somewhat numerous instances of the occasional occurrence of 
marginal ray-tracheids, such as are a characteristic feature of the living 
Abietineae. The genus Cunninghamia , as will be shown below, is of 
particular interest in this connexion, because it apparently offers the first 
case in which the conditions affecting the appearance of marginal tracheids 
have been elucidated in the case of the Cupressineae and Taxodineae. 
Figure 1, Plate XXXI, represents a transverse section of the wood of 
Cunninghamia sinensis under a moderate degree of magnification. The 
affinities of the wood are easily inferred from the considerable number of 
resin-cells, appearing as dark dots among the tracheids, and the absence of 
resin- canals, such as are found in those Abietineae which -more nearly 
resemble Pinus in their internal organization. It is the view of Professor 
Penhallow that the resin-canals of such forms as Pinus have been derived 
from a concentration of resin-cells, such as are found in Cunninghamia and 
other Cupressineous and Taxodineous genera. That this view can scarcely 
be maintained will be shown at a later stage. Attention was first drawn 
to the presence of ray-tracheids in Cunninghamia in longitudinal radial 
sections of a branch fourteen years old and rather over a centimetre in 
thickness. The segment of the branch was between two and three centi- 
metres in length, and presented no unusual features in the first eleven years 
of growth. In the last three years, however, there occurred here and there 
rays, characterized by the presence of marginal tracheids. Not more than 
two such rays were seen in any section, but in the considerable number of 
sections examined they showed themselves as distributed throughout the 
entire length of the piece of wood. In one case marginal tracheids were 
found on both upper and lower sides of the ray, but in the other instances 
