999 
Medullary Rays of Quercus. 
by side with broad, high, more or less undivided rays, others that are much 
divided (or smaller aggregated ones), arouses the suspicion that these 
secondary broad rays, however far from the centre they arise, are continuous 
at their inner extremities as a group of shallow thin rays. There are other 
possibilities, including the one that the divided ray may represent one 
undergoing division in an outward direction ; and such division does take 
place in Fagus. In regard to the matter, Eames (TO) states that in such 
later wood the origin of the broad ray is nearly always abrupt, and that 
‘ the transition from the lignified elements to [ray] parenchyma occurs 5 
generally within one to three annual rings ; but from this description 
it is not possible to form a mental picture of the exact mode of origin of 
such a ray. Again, in another genus, namely Alnus s branches show features 
similar to those in the seedling: in Alnus glutinosa it is well known that 
‘ false rays ’, which are so regular a feature in the main stem, are absent 
or rare in the branches. These facts suggest that the mode of origin 
of broad rays in Quercus and Alnus by a process of linking up of small 
rays may be merely of physiological significance. 
Yet putting aside the hypothesis that the seedling is the seat of 
ancestral characters, the ontogeny of the broad ray, as demonstrated by 
Eames, and its inception as a pencil of fine rays, does seem to suggest that 
it is phylogenetically compounded of these. But the same linking process 
would take place in entirely different circumstances. Supposing that the oak 
stem had always been characterized by the possession of broad high rays in 
at least rings at some distance from the centre, if we now consider the 
tangential (or more truly cylindrical) projection of the tangential view of 
a high broad ray in an outer annual ring upon the inmost annual ring, then 
not only all the small rays visible , on that elongated (inmost) projection, 
but also all the rays arising outside the inmost ring and lying within the 
truncated wedge formed by drawing lines parallel to the rays from the 
tangential outer outline of the thick ray to its outline in the inmost ring, 
would necessarily link themselves to the large ray or must end blindly 
outwards before reaching this. Again, if in the ancestral Quercus the 
primary rays were originally from their very commencement high and 
thick, but in the descendants had been split up only in the inner rings into 
a number of fine rays by reason of the cambium producing normal longitu¬ 
dinal constituents of the wood, then the same linking up of fine rays into the 
broad rays would be seen. 
This possibility of the existence of broad primary rays in Quercus and 
their gradual excavation to form a number of fine rays leads to the con¬ 
sideration of two fagaceous species— Fagus sylvatica and Quercus (. Pasania ) 
fenestrata. 
L. Jost (’ 01 ) states that in Fagus sylvatica the primary rays in their 
inmost region (near the pith) are high and undivided, but traced outwards 
