the Stems of Succulent Plants, SS 



markings, presenting a strong analogy to those of fossil plants ; 

 and I may venture to say that, if casts had been taken from 

 them, they would have been mistaken for real specimens of 

 these interesting remains. 



The plants, when chosen for examination, were old, and of 

 extremely luxuriant growth. The stems had acquired the 

 size of a man's arm, and were about five feet in height. They 

 were withdrawn from the hot-house during a sharp frost, by 

 which they were soon killed. The leaves dropped off, leaving 

 the rudiment more prominent and perfect than when their 

 removal happened by natural decay. After the death of the 

 plants, they were kept in the mould they occupied, and placed 

 in a shaded situation, where decomposition was allowed to 

 proceed slowly for the space of two years. During dry seasons 

 they were occasionally watered, and the upper part of the 

 stems was scooped out so as to admit moisture in the interior 

 soft parts when required : thus a partial fermentation was con- 

 tinued until the medullary substance became dissolved. 



The first change observable in the appearance of the epi- 

 dermis was a disposition to form regular ridges or risings in 

 the interstices between the marks left by the leaves and sub- 

 spinous nerve near them, preserving a reticulated pattern. 

 The hardness of the ligneous centre resisted decay for a long 

 time, and allowed the cortical covering to form its pattern 

 with considerable exactness ; and at last, by its own shrink- 

 ing, and the want of farther resistance from the nerve of 

 spine and leaf, the covering contracted in a longitudinal 

 direction, leaving the end of the wood projecting beyond the 

 upper part of the plant. 



The following drawings of the plants, taken at different 

 stages of decay, will be better understood than a lengthened 

 description. 



Fig, 7. represents the common appearance of the stem, 

 deprived of its leaves, before decay ; the tubercle and rudi- 

 ment of the leaf, in quincuncial order, scarcely rising above 

 the epidermis. 



Fig, 8. This figure shows the first angular depression 

 round the tubercle and leaf, caused by the shrinking of the 

 interior parts of the plant : the dried state of the cortex 

 opposing the contraction of its circumference. 



Fig, 9. is part of the same stem, contracting more equally 

 downwards, it having been more under the influence of 

 moisture than the lower end. It had now commenced a 

 wavy and rhomboidal cancellated figure, the elevated ridges 

 preserving an almost united wavy line from top to bottom. 



Fig. 10. The same as the last figure, having now attained 

 Vol. VII. — No. 37. d 



