€8 TRANSACTIONS OF THE [NOV. 23, 



most of them was found a green vegetable growth of imi- 

 celhilar plants. However, beneath some pieces the accumulated 

 black dirt shows the fractures to be of more remote origin. 



Piiotograj)hs of the obelisk, taken as soon as the shaft was 

 erected here (see *' Egyptian Obelisk," by Gorringe), show 

 numerous pieces broken out of the edges of the sluift, while 

 the lower corners resting on the "crabs" and plinth have 

 scaled off, as nearly all stone does under great; pressure. The 

 photograi)hs show also that at least one side of the plinth had 

 flaked before erection here, and all sides of the lower i)art of the 

 shaft. The hieroglyphics are nearly obliterated on one entire 

 side of the shaft, and their distinctness gone on about two-thirds 

 of another side. 



Placing a fragment of th(> rock under the microscope, portions 

 of it siiow decided disintegration, parts of the hornblende being 

 broken down and dissolved, while some of the white feldspar 

 is broken into such minute fragments that they exhibit the 

 Brownian movement when placed in water. In the minute 

 crevices can be seen the green cells of vegetable growth, and on 

 cither side of the crevice may sometimes be seen, with the micro- 

 scope, the rosy hue indicating internal strains in the very minute 

 fragments, a sligiit increase of which would complete the frac- 

 ture; and it is possible that the growing cells may furnish the 

 necessary strain. 



The green ceils belong to the lowest class of vegetation, and, 

 containing chlorophyll, are hence not fungoid. One class of the 

 cells is rod-shaped, from two to six micro-millimetres in lengtii, 

 by one and one-half to two in diameter, the sides being straight, 

 with slightly convex ends. On some pieces of rock, these were 

 mostly in single cells, though two and three were connected in a 

 straight line, never branched. These cells were attached to 

 small microscopic fragments in colonies of one to five iumdred, 

 apparently by a gelatinous substance, and not easily detached 

 after a moment's immersion in water. These cells require a 

 |)Ower of about five hundred to show the cell-wall and the 

 internal spore (?). Up to the present time, I have not been able 

 to find a similar described form. 



In addition to the oblong form, another class of round cells, 

 belonging to the genus Protococcvs, was found on the most dis- 

 integrated fragments. Some were round ; others were sub- 

 dividing into twos, quite similar to tiie figures given in the 

 Botanical Atlas of Frolococcus plnvialis. So far, I have not 

 found subdivisions of cells into threes and fours, as is found in 

 the Proiocciis viridis {?), so abundant on the trees in the Cen- 

 tral Park near the obelisk. Besides these cells, spores of many 

 other forms of vegetable life were found in abundance. 



