Origin of ‘ Transfusion Tissue \ 
981 
3. The relative amounts of centripetal xylem and of transfusion tissue 
may be summarized thus :■—• 
Genus. 
Amount of centripetal xylem. Amount of transfusion tissue. 
Tax us 
Cephalotaxus 
Podocarpus 
Araucaria 
Finns 
Sequoia 
Sciadopitys 
Cupressus 
Thuja 
Juniperus 
Fair amount 
More than in other genera 
None 
None 
None 
None 
Little 
Little 
None 
Fair amount 
Fair amount 
About as in Taxus 
Fair amount 
Not always easy to distin¬ 
guish. It was found by 
Hill and de Fraine (loc. 
cit., II) 1 
Little 
Fair amount 
More than in other genera 
except Thuja 
Little 
Much 
Little 
It thus appears that there is no correlation between the amounts 
of the two tissues. One does not wax as the other wanes. On the other 
hand the amount of transfusion tissue is greatest in those cotyledons which 
are largest and which perform assimilatory functions for the longest time 
unaided by other leaves. 
In contradistinction to what has been noted in Chick’s paper on 
Torreya , 2 the transfusion tissue of these cotyledons was not more abundant 
at the tip, except as noted under Sciadopitys verticillata . It was at first 
thought that ease in distinguishing it would be gained by treating the sec¬ 
tions with phloroglucin, but the only result that this led to was the conclusion 
that the transfusion tissue must lignify late, since even when it was dis¬ 
tinguishable in a section it did not always take on the red colour. 
Treatment with aniline sulphate confirmed this opinion. The middle of the 
cotyledon almost invariably showed most of the tissue. 
In addition to the above facts two others emerged with some clearness 
during the investigation. 
1. That the size of the transfusion elements is enormously dispro¬ 
portionate to that of the centripetal wood when present, and also to that of 
the centrifugal wood. At the same time it is necessary to observe that 
those nearest to the xylem of the bundle are as a rule smaller than those 
further out. The transfusion tracheides are largest of all in Sciadopitys 
verticillata (Fig. 1). 
2. The transfusion tissue when it appears in the adaxial position never 
abuts directly on the xylem of the bundle; it is always separated by 
at least one layer of parenchyma. This seems a point of some importance 
in view of the transition emphasized by Worsdell; it agrees with the 
remark of Miss Chick that the transfusion tissue appeared to be developing 
from the parenchyma. 
Although not directly concerned with the question of the origin of 
1 Annals of Botany, vol. xxiii, p. 213. 2 Loc. cit. 
