48 - 



all those bodies which expand in becoming solid are similarly 

 affected by pressure, while the other bodies which like wax con- 

 tract in congealing, have their melting point raised under the 

 same circumstances. 



As yet we are too little acquainted with the habitudes of the 

 various rocks in these respects, to decide as to the extent to which 

 the one or other of these opposite agencies of pressure upon the 

 melting point may operate in the interior of the globe, or to form 

 any valid conclusion as to their aggregate effect upon the com- 

 puted thickness of the crust. 



Dr. C. T. Jackson presented a box of the silky growth 

 from the base of the fronds of tree-ferns growing at the 

 Sandwich Islands ; this substance is used by the natives 

 for stuffing beds. Something of the kind is found in 

 our own ferns. 



Dr. Jackson also presented, in the name of Mr. C. K. 

 Landis of Philadelphia, a specimen of a fungous growth 

 called " Indian Bread," or " Tuckahoe," in the Southern 

 States. He found it to contain no starch, but cellulose 

 and considerable mucilage. It is sometimes eaten. 



Mr. Sprague said that it was an underground growth, 

 being a fungus called Pachyma coeos. It is supposed 

 to be an arrested stage of some unknown plant, produc- 

 ing only a large sclerotioid mass, and never reaching a 

 perfect state. Such is frequently the case among fungi, 

 the whole genus Sclerotium being a heterogenous as- 

 semblage of inform growths, which are the non-devel- 

 oped stages of dissimilar plants. 



Mr. J. M. Barnard announced that the desired appro- 

 priation for a new and illustrated edition of Dr. Harris's 

 work on insects injurious to vegetation, had been made 



by the legislature. 



« 

 Messrs. C. Allen Browne, and George H. Hepworth, 



of Boston, and Mr. Charles H. Morse, of Cambridge, 



were elected Resident Members. 



