10 ; Phragmipedium, 53 ; Pleurothallis, 17. This will indicate 

 the value of the collection for a comparative study of forms 

 from the new world. 



The Old World is also well represented by about thirty-one 

 genera and three hundred and sixteen species. Among those un- 

 usual in cultivation are : Ceratostylis, Mystacidium, Spathoglottis, 

 Listrostachys, Tainia, Neobenthamia, Otochilus, and Oberonia. 

 The following genera are represented by five or more species or 

 varieties: Eria, 13; Cirrhopetalum, 10; Sarcanthus, 5; Cym- 

 bidium, 12 ; Platy dints, 5 ; Bulbophyllum, 25 ; Angraecum, 14; 

 Coelogyne, 20; Dendrobium, 52; Vanda, 11; and Paphiopedi- 

 lum, 108. The genus last named contains the largest repre- 

 sentation in the whole collection, and embraces some plants of 

 great value, now rather difficult to obtain. 



Of genera which are common to both the Old World and the 

 New are : Polystachya, Liparis, Vanilla, Spiranthes, Eulophia, and 

 Microstylis. 



The entire collection contains about 1,530 plants, representing 

 nearly 100 genera and about 750 species and varieties. A num- 

 ber of the genera and many of the species were not previously 

 in the Garden collections. It is hardly necessary to state that the 

 acquisition of this material adds greatly to the value of the 

 Garden collections, not only for the purposes of study, but also 

 from the viewpoint of beauty and decoration. 



George V. Nash. 



THE SELF-PRUNING OF TREES, 

 itural pruning of trees has long been well known. By 

 runing is meant the loss of certain branches after their 

 msed usually by overshading and consequent poor 

 Thus is explained the lack of lower branches on trees 

 close together in a forest. In this process the tree 

 massive until the branch is dead, after which the dead 

 cut off by the formation of a "collar" of tissue by the 



suit of the action of environmental forces outside the tree! 



