22 PROCEEDINGS OF THE ACADEMY OF [1885. 



the lobes. Another worm decapitated at the same date, though 

 of apparently weaker vitality, had regenerated all the excised 

 portions, and showed a completely formed brain, with lobes of 

 the normal size in contact. 



Messrs. Burnett Landreth and J. Addison Campbell, and Mrs. 

 Cornelius Stevenson, were elected members. 



February 3. 

 Mr. George W. Tryon, Jr., in the chair. 

 Twenty-seven persons present. 



February 10. 



Rev. H. C. McCook, D.D., Vice-President, in the chair. 



Twenty-two persons present. 



The Internal Cambium Ring in Gehemium sempervirens. — 

 Dr. J. T. Rothrock, at the meeting of the Botanical Section held 

 February 9, called attention to the internal cambium ring in the 

 stem of Gehemium sempervirens. It might well be designated 

 as the inner cambium. His attention was attracted by the fact 

 that in a stem of three-eighths of an inch diameter, the pith was 

 actually less in diameter than in a twig of a quarter the size of the 

 stem. Microscopic examination showed that in the larger stem 

 there were ordinarily four or more points, at which a well-defined 

 swelling curved inward from the circumference of what should 

 have been the pith-cavit}'. These swellings resolved themselves 

 when closely examined into : — 



1. Toward the centre an imperfectly defined membrane, resemb- 

 ling cuticle, which was not always present. 



2. One or more rows of large cells like the parenchyma we find 

 under the epidermal layer. 



3. Several poorly defined layers of smaller cells, such as often 

 mark the limits of growth in bark. 



4. The frequent presence of bast fibres or of sclerenchyma 

 cells. 



5. An evident layer of thin-walled, square cells, closely resemb- 

 ling, though somewhat smaller than those of the external cambium. 

 They showed signs of division, which indicated that they were 

 still a living tissue. 



These facts explained at once why the pith was constantly 

 being encroached upon until it at length almost disappeared. 

 The medullary rays dipped down through, and widened out, in 



