Foliar Ray in the Wood of the Dicotyledons . 657 
may be seen five depressed segments. In this twig the foliar ray has 
disappeared except from the immediate vicinity of the leaf-traces. The 
normal twig possesses a circular outline, and the foliar ray is not con- 
spicuously developed at the node. This recurrence of depressed segments 
in vigorous shoots of Castanea indicates that five pairs of approximated 
lateral leaf-trace rays existed formerly in the mature twigs of these plants, 
and have disappeared except from the nodes of very vigorous stems. In 
Castanopsis indications of depressed segments which were once a well- 
developed feature of the plant persist in the normal mature twigs. A cross- 
section of the node of Castanopsis hystrix is illustrated in PI. LXIII, Fig. 16. 
Two segments (y) are more strongly depressed upon the upper side of the 
photomicrograph, due to the fact that the rays related to the lateral leaf- 
traces are persistent at the node. Owing to the phyllotaxy of the plant 
the three remaining segments (x) are less strongly depressed. Fig. 14 
shows a cross-section of the mature stem of Castanopsis indica. In this 
species the five depressed segments are more persistent between the nodes, 
and indicate that the reduction of the foliar ray is less complete in this 
plant than in the preceding species. In Fig. 13 may be seen the cross- 
section of a mature twig of Castanopsis trihtdoides , a plant whose structure 
resembles that of Quercus , since the lateral leaf-trace rays are strongly 
developed in the wood of small twigs. A careful study of the life-history of 
the plant reveals the fact that the aggregated rays are disappearing in many 
portions of the root and stem. In PI. LXII, Figs. 11 and 12 are illustrated 
the remains of aggregate rays which were once strongly developed by the 
cambium to maintain the proper proportion of ray tissue in the widening 
stem and root. These facts, considered in connexion with evidence afforded 
by the recapitulation of primitive characters which occur in vigorous 
mature ramifications, nodes, and traumatic regions, point conclusively to 
the reduction of foliar rays in certain Fagales, and indicate that Castanopsis 
and Castanea are reduced members of the oak family, just as Alnns mollis , 
A. acuminata , and A. yasha must be considered reduced species of the 
genus Alnus. 
The uniseriate rayed species of the Salicales ( 9 ) and Sapindales (10) 
have been studied by Miss Holden, and have been found to represent 
a reduced condition where complex ray structures have been lost in a 
reversion to the primitive uniseriate type, but among the higher families 
of Dicotyledonous plants the uniseriate condition has resulted largely from 
the reduction of foliar rays of the diffused type rather than of the 
a gg re g ate or compound types. 
