42 T/iompson — 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, Gerard, 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 Herail 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. Ill, 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 Ipomcea 

 versicolor. Annals of Bot., Vol. V, 1891, 



Herail. — Recherches sur I'Anatomie comparee de la Tige 

 des Dicotyledones. Ann. des Sc. Nat., Bot. Ser. VII, T. II, 

 1885. 



Lamounette. — Recherches sur I'origine morphologique du 

 Liber Interne. Ann. des Sc. Nat. Bot., Ser. VII, T. XI, 1891. 



Literature Relating to Gelsemium. 



Gelsemium senipervirens is commonly known in the South- 

 ern States as the " Yellow Jessamine," and is placed in the 

 order Loganiaceae by Solereder, Engler and Prantl, and Gray ; 

 in the order Apocynaceae by Baillon, Le Maout and Decaisne. 



In the Laboratory Contributions from the Biological Depart- 



