(i2 4 ) 



and the methods by which the various plant structures 

 have been preserved. A number of specimens of silicified 

 woods show the method of preservation by what is known 

 as petrifaction, or conversion into stone, in which the 

 woody structure is replaced by mineral matter. Other 

 specimens show preservation by incrustation, in which 

 mosses and the stems of reeds are coated or incrusted by 

 mineral matter deposited from springs; while on the upper 

 shelf on the top of the case are logs and stumps from old 

 swamps and interglacial deposits, in which the wood has 

 been partially carbonized, or converted into lignite, by 

 the slow process of natural distillation. This process 

 represents the beginning of the conversion of vegetable 

 tissue into coal. 



LECTURES 



Other features of the museum building include the large 

 public lecture hall, with a seating capacity of over seven 

 hundred, which occupies the western end of the basement. 

 It is equipped with an electric projection-lantern, and free 

 public popular lectures covering a wide field of botanical 

 and horticultural subjects are delivered here on Saturday 

 afternoons from spring to autumn; these are fully illustrated 

 by means of a very extensive collection of lantern slides 

 owned by the Garden which is constantly being increased. 

 A noteworthy part of this collection is the series of delicately 

 and accurately colored slides of flowers, fruits, trees and 

 shrubs, by Mrs. Adelaide S. Van Brunt, from photographs 

 made during many years by her late husband, Cornelius 

 Van Brunt. 



The Horticultural Society of New York holds several of 

 its monthly meetings at the Garden, using the large lecture 

 hall, and also uses the basement museum hall adjacent for 

 the purpose of exhibitions. 



The Torrey Botanical Club holds monthly meetings from 

 October to May, on the afternoon of the last Wednesday of 

 each month, in the museum building, and several of its field 



