frt>m ike Stems of Vegetables. 331 



1. The depositions of ice are entirely confined to the im- 

 mediate neighbourhood of the roots of the plants, the upper 

 parts of the tall unbroken stalks being quite free from them. 

 They frequently commence two or three inches from the 

 ground, and extend from three to four inches along the axis 

 of the stem. It is proper to state, that at this season the stalks 

 are dead and quite diy to within about six inches of the earth, 

 below which they are generally green and succulent. The 

 plant has a large and porous pith, which is always saturated 

 with moisture as high as six or seven inches from the base of 

 the stem. 



2. The ice emanates in a kind of riband- or frill-shaped 

 wavy friable semi-pellucid excrescence, "as if protruded in 

 a soft state from the stem, from longitudinal fissures in its 

 sides." As Sir John Herschel remarks, " The structure of 

 the ribands is fibrous, like that of the fibrous variety of gyp- 

 sum, presenting a glossy silky surface, the direction of the 

 fibres being at right angles to the stem, or horizontal." Ac- 

 cording to my observations, the number of ribands vary from 

 1 to 5. All of them issue from the stem in vertical or longi- 

 tudinal linesj which are not always symmetrically disposed 

 around the axis. Judging from the engraving given by Sir 

 John Herschel, the Pluchea exhibits the phsenomenon much 

 more conspicuously and beautifully than the stumps of helid- 

 tropes observed by him. I have frequently observed the icy 

 excrescences to exceed five inches in length ; and when thus 

 elongated, they are usually curled ; often so much so, as to 

 bring the remote extremity of the frill nearly in contact with 

 its line of attachment to the stalk. 



3. " Although," as Sir John Herschel correctly observes, 

 " the icy sheets appeared to have been protruded from the 

 interior of the stem, yet on examination they were found to 

 terminate sharply at its surface, adhering to it so lightly as to 

 render it impossible to handle a specimen without detaching 

 them, and in no instance connected with any formation of ice 

 within ; on the contrary, the majority of the stems were sound 

 and solid, and many of them still green when cut. The point 

 of attachment of the ice was, however, always on the surface 

 of the "wood, beneath the outer bark or epidermis, which the 

 frozen sheets had in every instance stripped off and forced 

 out to a distance. Where the fringes were large and well- 

 deVeloped, the bark had quite fallen off; but in those cases 

 where it adhered more strongly, it seemed to have prevented 

 their free expansion ; and in such instances the stem presented 

 the singular appearance of a thick massive coating of ice in- 

 terposed between the wood and its integument, which Wfls 



Z2 



