A Reconsideration of the Origin of ‘ Transfusion 
Tissue \ 
BY 
M. GERALDINE CARTER, B.Sc. 
Goldsmiths' College , University of London. 
With four Figures in the Text. 
RANSFUSION tissue in gymnospermous leaves has been described 
1 by a large number of botanists during the last sixty to seventy years. 
Zimmermann, in a paper on this subject published in 1880, 1 gave the names 
of Mohl, Karsten, Thomas, Hartig, Frank, Sachs, Bertrand, and de Bary, as 
those who had written about it before that date, and he himself described the 
position and nature of the thickening of the transfusion tissue in twenty-one 
species of Coniferae. Towards the end of the paper he stated that he found 
its varied orientation and great increase towards the tip of the leaf difficul¬ 
ties in the way of accepting Mohrs assumption that it served for the 
conduction of sap. 
Transfusion tissue of the ordinary kind, as distinguished from the acces¬ 
sory transfusion tissue of Cycas to which this paper does not further refer, 
has been found by Stopes 2 in Cordaites also, so that it is known in fossil 
Gym nosperms as well as living ones. 
But it is not only in Gymnosperms that transfusion tissue occurs ; 
Scott 3 describes it in the leaves of Lycopods and thinks that even gymno- 
spermous transfusion tissue may be comparable with what is found there, 4 
and Boodle and Worsdell in a paper on Casttariiia b pointed out that 
‘ transfusion elements occur in the ridges of the young stem and of the 
leaves ’. They considered, however, that these had a different origin 
and nature from the transfusion tissue so well known in the leaves of 
Gymnosperms. The pits of this transfusion tissue are, moreover, simple, 
while in gymnospermous transfusion tissue bordered pits are found. 
Other writers since Zimmermann have shown interest in the last-named 
kind of tracheidal elements. Strasburger devotes some pages to it in the 
1 Ueber das Transfusionsgewebe. Flora, 1880. 2 New Phytologist, vol, ii, 1903, p. 91. 
3 Studies in Fossil Botany, pt. i, pp. 160, 224. 4 Studies, pt. ii, p. 655. 
5 Annals of Botany, vol. vii. 
[Annals of Botany, Vol. XXV. No. C. October, 1911.] 
3 S 2 
