Proceedings of the Club 691 



Dr. Underwood called attention to the relative amount of sun- 

 light in tropical and in northern regions, pointing out that the 

 amount of light is much greater north of the tropics though more 

 oblique. 



Discussion followed regarding relations of moisture. Dr. 

 Schoeney referred to the peculiar erect and densely appressed 

 stems assumed by a cespitose Opuntia about Boulder, Colorado. 



Dr. MacDougal spoke of the remarkable degree to which 

 many of the cacti have adapted themselves to xerophytic condi- 

 tions, so that they lose water less than one-three hundredth as 

 readily as in ordinary plant structures in similar positions. 



Dr. Rydberg referred to the permanent moisture found within 

 10 or 12 inches of the surface in the dry sandhills of Nebraska. 



The second paper was by Dr. P. A. Rydberg, " Revision of 

 Limnorchis and Piperia" which was printed in full in the Novem- 

 ber Bulletin. 



Reference was made by Mr. G. H. Watson to a remarkable 

 growth near Ellenville, New York, where two trees not only differ- 

 ent in species but in family had so twisted together as to become 

 incorporated, and in response to the expressed appreciation of its 

 significance, he promised further investigation and a photograph 

 of the trees. 



Edward S. Burgess, 



Secretary. 



