Internal Phloem in Gelsemium sempervirens. Ait. 43 



ment of the University of Pennsylvania for 1884, J. G. Shoe- 

 maker has a few notes on the stem of Gelsemium. He remarks 

 the widening of the medullary rays, and " the tendency of the 

 pith to be penetrated by several plates of large thin-walled 

 cells, which divide the pith more or less perfectly into four 

 portions." 



Professor Rothrock, in February, 1885, made a short verbal 

 communication to the Philadelphia Academy of Natural 

 Sciences concerning this stem. His attention was attracted by 

 the fact that the diameter of the pith is greater in a very young 

 twig than in a stem four times its size. He notes the presence 

 of the four medullary phloem patches, and their encroachment 

 upon the pith area. 



A great deal of work has been done upon Gelsemium from 

 a chemical and pharmaceutical standpoint, but its structure 

 and development have not been thoroughly worked out. The 

 root contains an alkaloid gelsemin, which is very poisonous, 

 but is a valuable medicine when taken in proper quantities. The 

 medicinal properties of Gelsemium were accidentally discovered 

 about the middle of this century. An interesting account of 

 the discovery and the primitive method of extracting the poi- 

 sonous principle from the root is given by William Proctor, Jr., 

 in the "American Journal of Pharmacy" for 1852. 



Other records of the investigations upon the alkaloid gelse- 

 min are to be found in later numbers of this journal, and in the 

 " Proceedings of the American Pharmaceutical Association." 



Histology of a One-year-old Stem. 



A transverse section, about i mm. in diameter, of an inter- 

 node at the close of the first year's growth shows the following 

 structure (Plate IX, Fig. i). Externally are three to four lay- 

 ers of cork, still covered in places by the prominently ridged 

 cuticle ; next is the cortex, consisting of a zone of parenchyma 

 four to five cells deep, rich in protoplasm and containing abund - 

 ant chlorophyll and starch grains. A ring of large sclerotic 



