The Rev. P. Keith on the Internal Structure of Plants. 1 15 



the bulb of the Tulip is taken up in the beginning of the 

 month of January, and carefully bisected in a line passing 

 through its longitudinal axis, the petals, the stamens, the 

 pistil, and the incipient stem may be already all distinctly per- 

 ceived, small and delicate in their appearance, but complete 

 in all their parts. 



The Bud. — If the scales of a bud are stripped off, and dis- 

 sected under the microscope, they will be found to consist of a 

 thin epidermis, inclosing a pulp interspersed with a network 

 of fibres. But buds produce either leaves, or flowers, or both, 

 and it was to be presumed that leaves and flowers must exist, 

 in an incipient state, in the bud, long before the period of 

 their natural evolution; which presumption the dissection of 

 buds has shown to be the fact, as the following example will 

 demonstrate. In the month of March 1810, I opened up a 

 bud of the Horse Chestnut that had not yet burst its scales. 

 The scales, which were about fifteen or sixteen in number, be- 

 ing removed, were found to contain one pair of opposite leaves, 

 now laid bare, the divisions of which were closely matted to- 

 gether with a fine down. The leaves upon being opened were 

 found to inclose a flower-spike, consisting of not less than 

 a hundred florets compactly crowded together, and each en- 

 veloped by its own downy calyx, which when opened disco- 

 vered the corolla, stamens and pistil distinct, the rudiments 

 of the future fruit being also discernible in the ovary. 



The Flower. — If the calyx or corolla is carefully dissected 

 with the assistance of a good glass, it will be found to consist 

 of the following several and distinct parts: an epidermis, or 

 external envelope ; a parenchyma, or soft and pulpy mass ; and 

 bundles of longitudinal threads or fibres originating at the 

 base, and subdividing and ramifying throughout the expan- 

 sion, so as to form a thin and flat network. The stamens and 

 pistils seem to consist merely of a fine epidermis, inclosing a 

 soft and pulpy parenchyma, without exhibiting any traces of 

 longitudinal threads or fibres, or but very rarely so. The 

 filaments of the Tulip are tubular, which is, as I believe, a 

 very rare occurrence. 



The Leaf.— -The leaf, like the calyx and corolla, is found 

 upon dissection to consist of an epidermis, a parenchyma, 

 and multitudes of interspersed fibres. Take a leaf of com- 

 mon sorrel, and tear it asunder, either in a transverse or 

 longitudinal direction, and fragments of a fine and transpa- 

 rent pellicle will be seen projecting beyond the edge of the 

 torn part. This is the epidermis. When the epidermis is 

 stripped off, the parenchyma appears, — a green and pulpy 

 mass interspersed with the prolongations of the fibres of the 



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