42 Tiompson—The Structure and Development of 
many of the later workers. From that time onward the num- 
ber of investigators and the detail with which the work has 
been carried out have steadily increased. The most important 
contributions to the literature of this subject have been made 
‘by Vesque, Weiss, Russow, Petersen, Van Tieghem, Fischer, 
Scott, Gérard, Herail, Lignier, Leonhard and Lamounette. 
Various views are held by different writers upon the relation 
between the internal phloem and the other parts of the bundle. 
Some believe with de Bary that an actual bicollateral condition 
exists, and that the internal phloem is as much a part of the 
bundle as the external, and is of similar origin. Others, nota- 
bly the French botanists Hérail and Lamounette, believe that 
the internal phloem is independent of the bundle and of 
different origin. 
The following papers have been specially consulted: 
Solereder, H. Ueber den systematischen Werth der Holz- 
structur bei den Dicotyledonen, 1885. 
Scott and Brebner.—On the Anatomy and Histogeny of 
Strychnos. Annals of Bot., Vol. III, 1889. 
Scott and Brebner.—On Internal Phloem in the Root and 
Stem of Dicotyledons. Annals of Bot., Vol. V, 1891. 
D. H. Scott.—On Some Points in the Anatomy of /pomea 
versicolor. Annals of Bot., Vol. V, 1891. 
Hérail.—Recherches sur l’Anatomie comparée de la Tige 
des Dicotyledones. Ann. des Sc. Nat., Bot. Sér. VII, T. II, 
1885. 
Lamounette.—Recherches sur l’origine morphologique du 
Liber Interne. Ann. des Sc. Nat. Bot., Sér. VII, T. XI, 1891. 
LITERATURE RELATING TO GELSEMIUM. 
Gelsemium sempervirens is commonly known in the South- 
ern States as the “ Yellow Jessamine,” and is placed in the 
order Loganiacee by Solereder, Engler and Prantl, and Gray ; 
in the order Apocynacez by Baillon, Le Maout and Decaisne. 
In the Laboratory Contributions from the Biological Depart- 
