254 



Philadelphia, and showing that Institution to be in a condi- 

 tion of activity and prosperity well calculated to excite emu- 

 lation. 



Mr. Teschemacher exhibited the stem of an arborescent 

 Yucca, the head of which had been destroyed — 



It had thrown out numerous adventitious buds from the lower 

 part. These buds were arranged in a regular spiral direction, 

 and the whole appearance of the stem resembled very closely 

 the figure of Halonia regularis, (Lindl. & Button, vol. iii. tab. 

 228.) This, being the abnormal state of this plant, might, he 

 thought, account for the scarcity of specimens of Halonia. 



He also exhibited transverse sections of these buds, showing 

 their origin in the central cellular substance of the stem, the ex- 

 ternal portion of the stem (the false bark) being a mass of closely 

 compact vascular matter one-fourth to one-half an inch thick, 

 through which the buds pass, in a conical form ; he compared 

 these with a beautiful specimen of some symmetrically arranged 

 conical forms, impressed with vascular appearances, found in the 

 body of the Anthracite coal of Pennsylvania. 



He also presented some conical forms, composed of distinct 

 and separate fibres, in the fine interstices of which were numer- 

 ous microscopic but perfect crystals of Carbonate of Iron. These 

 specimens he had obtained thirty years ago, from coal and iron 

 mines in England ; but until the present time, he had not been 

 able to get any light on their singular but very distinct structure. 

 Two of them are still embedded in the rocky mass. He now 

 thinks these conical forms are of vegetable origin. 



He remarked, that Analogy, not Identity, was the object to be 

 pursued in our present researches into fossil vegetation ; he 

 thought the analogy close, between the false vascular bark of the 

 Yucca and the so-called bark of many Sigillarise; that the slight 

 impressions on the soft internal part of the Yucca, left by the 

 apices of the conical buds, were analogous to those seen on Sigil- 

 larise on removing the carbonized bark. 



He thought it not improbable, from the great resemblance of 

 the scars of buds on the external part of the stem of Yucca, to 

 the markings on Sigillariae and Lepidodendra, that many of these 

 markings are scars of buds, instead of those of leaves. He ex- 



