Comparative Anatomy of the Casuarineae . 261 
which is so entirely different from that of the internode ; 
instead of the typical Gnetum - structure we found elements 
(vessels and tracheides) possessing characters intermediate 
between Ephedra and Gnetum , the mode of perforation of the 
vessels more nearly resembling that in the former plant than 
the latter ; we have fully entered into the description of this 
phenomenon in the foregoing pages. 
The above investigation was first begun at the suggestion 
of Dr. D. H. Scott, and has been carried out in the Botanical 
Laboratory of the Royal College of Science, South Kensington. 
The examination of the stem and leaf-sheath was begun by 
L. A. Boodle ; the completion of this, together with the re- 
maining part of the paper, was carried out by W. C. WorsdelL 
We wish to express our thanks to Dr. D. H. Scott and Prof. 
J. B. Farmer for their kind help and suggestions, during the 
earlier and later parts of the work respectively. 
In conclusion we must particularly mention our indebted- 
ness to Mr. Carruthers and to Mr. Rendle of the Natural 
History Museum, for having given us facilities for examining 
dried material of several species of Gnetum in the Herbarium. 
We have also to thank the Director of the Royal Gardens, 
Kew, for kindly supplying us with living specimens of various 
species of Casuarina. 
