172 



May 27, 1908 



The Club was called to order at the Museum Building of the 

 New York Botanical Garden at 4 p. m. by Vice-President John 

 Hendley Barnhart. Eight persons were present. After the 

 reading and approval of the minutes for May 12, 1908, the an- 

 nounced scientific program was presented. The following ab- 

 stracts were prepared by the authors of the papers : 



" The North American Species of Zygodoii," by Mrs. N. L. 

 Britton. 



Attention was called to the fact that Zygodon viridissinms is a 

 rare species, having been found only a i&v^ times in the high 

 mountains of the southern Alleghanies and northern New York. 

 It is usually sterile and propagates by septate brood-bodies, 

 borne iii clusters in the axils of the leaves. Fruiting specimens, 

 collected by Dr. J. K. Small on the summit of White Top, Vir- 

 ginia, showed that the peristome is absent, though all the cap- 

 sules found were either too young or too old for satisfactory de- 

 termination. A comparison with specimens collected by Drum- 

 mond near Hudson Bay show that the latter belong to Zygodon 

 rnpestris which is variously placed by European authors, either 

 as a species or a variety of Z. viridissinms. Sterile specimens of 

 Zygodon gracilis have been recently discovered in North Caro- 

 lina by Dr. A. J. Grout. Zygodon excelsns, whose fruit is also 

 still unknown, appears to be more closely related to Leptodontiiim 

 than to Zygodon. 



" The Acceleration of Senescence by Radium- Rays," by C. 

 Stuart Gager. 



In view of the fact already well known, that, as old age ap- 

 proaches, the size of the cell-nucleus, becomes less relative to that 

 of the cell, measurements were made to see if this relation was 

 affected by exposure to radium rays. It was found that in cells 

 near the root-tip of Zca mays the diameter of the nucleus was 

 35.5 per cent, that of the cells, in unexposed plants, but only 

 33.33 per cent, in roots exposed to radium rays. This is some 

 evidence that exposure to radium rays accelerates the approach 

 of the period of senesence. 



" A Collection of Philippine P'ungi," by W. A. Murrill. 



