NATURAL SCIENCES OF PHILADELPHIA. 23 



It was as true of trees as of the clover plant. Roots elevated 

 found the cavities below partially filled, and could not thus per- 

 mit of the tree being quite as low as before. Dr. Laphara thought 

 that in the West large old trees blew over much more readily than 

 younger ones, though the comparative weight of head and roots 

 were proportionally the s^ame, chiefly because the older trees had 

 been drawn nearer the surface. 



Mr. M. also remarked that the belief was very prevalent among 

 woodmen, that the numerous large roots which marked the sur- 

 face of an old piece of woodland " like railroads on a modern 

 map" were not originally near the top, but had grown to the sur- 

 face. He had always supposed these also to result from thicken- 

 ing, but he now had seen some cases in which this would not ac- 

 count for it, and only the frost-lifting power would. So, also, in 

 many swampy pieces of land, much of the vegetation had the 

 appearance of tussocks, and the land as if it had been washed 

 awa^' from around the roots. It was not probablj'^ from annual 

 growths, but from gradual liftings of the plants from year to 

 year and the filling in of the spaces beneath by the soft mud. 



It was likely that one of the chief offices of the tap roots was 

 to guard the tree from this frost lifting as much as possible. His 

 impression was that the trees of tropical climates had not near 

 the development of tap roots which are found in the more northern 

 ones, but this was a matter for further investigation. 



March IT. 

 The President, Dr. Ruschenberger, in the chair. 

 Twenty members present. 

 The death of Dr. Wm. S, Halsev was announced. 



March 24, 

 The President, Dr, Ruschenberger, in the chair. 

 Twentj'-seven members present. 



On Actinophrys sol. Prof. Leidy, after describing the structure 

 and habits of this curious rhizopod, said that he had recently' 

 observed it in a condition which he had not seen described. He 

 had accidentally found two individuals including between them a 

 finely granular rayless sphere nearly as large as the animals them- 

 selves. These measured, independently of the rays, 0.064 mm. 

 in diameter; tlie included sphere 0.06 mm. He supposed that 

 he had been so fortunate as to find two individuals of Actinoj)hrys 

 in conjunction with the production of an ovum. 



