ire 



THE CABINET OF NATURAL HISTORY 



the only alterations perceptible in their external con<lition 

 were a small decrease in bulk, and a slightly wrinkled ap- 

 pearance, pirticularly of the abdomen: but their functions 

 were seemingly unimpaired; for on warm days, or when 

 excited by artificial heat, they were lively in their mo- 

 tions, and to the last continued to produce their threads, 

 which were often destroyed for the purpose of ascertaining 

 whether tliey would be replaced by others with apparently 

 the same facility as at the time of their capture. 



It is particularl}' deserving of notice, that these insects, 

 though unable to climb up the smooth perpendicular sides 

 of the phials on their first introduction, soon contrived to 

 traverse the interior of tlieir prisons in every direction. 



In order to illustrate their manner of proceeding on this 

 occasion, the case of an individual has been selected for de- 

 scription, — the same method, with a few trivial modifica- 

 tions, being pursued by all. Elevating the abdomen, and 

 pressing the spinning-apparatus against the side of the 

 phial, this spider emitted from its papillae a little viscous 

 fluid, which on exposure to the air hardened into a minute 

 semi-transparent speck; then moving to a short distance, 

 and drawing out a thread after it, one end of which re- 

 mained fixed to the spot it had connected this filament 

 with another part of the phial by applying the spinners as 

 before. Several lines being thus produced, the spider 

 speedily raising itself upon them above the bottom of the 

 phial, promoted its undertaking by repeating the process 

 just described; every step so gained enabling it to carry its 

 operations still higiier. 



From the cylindrical figure of the phial, it follows that 

 all the lines attached to its sides by their extremities, such 

 as were vertical alone excepted, formed with those sides 

 chords to arcs of various magnitudes. Lowering itself from 

 one of these chords to another, and applying the spinners 

 to each in succession, the spider soon connected the whole 

 of them together by a line; then ascending again to the 

 greatest altitude it could attain, and dropping down by a 

 thread to the bottom of the phial, over which it walked to 

 the opposite side; it there drew the thread tight and made 

 it fast, having prevented it from coming in contact with 

 the glass previously by raising the abdomen a little. To 

 this oblique line it united others, extending them in differ- 

 ent directions, till by these means it cstablislicd a commu- 

 nication with every part of the phial. As there was some 

 difficulty in tracing these operations with the unassisted 

 eye, lenses of the magnifying powers of six and eight were 

 employed. 



The spiders seen ascending into the atmosphere on the 

 1st of October were of two distinct species; but as the 

 technical difference of insects has engaged only a small 

 share of my attention, I shall leave the task of identifying 



them to those who are more familar than myself with this 

 branch of entomology. The subjoined remarks on some 

 of the characteristics of these insects, which are more con- 

 veniently illustrated by the pen than the pencil, may serve 

 to facilitate this object. 



One species has four of its eight eyes much larger than 

 the other four. Two pairs situated in the front or fore- 

 part of the head are arranged thus °. .°, the relative size of 

 the dots being nearly the same as that of the eyes. The 

 other pair of small ones is placed in the upper part of the 

 head, and on each side of it one of the remaining pair of 

 large eyes is seated. The spider has the abdomen rather 

 depressed; the anterior limbs, which it raises in a menacing 

 manner when any thing approaches it, are longer than 

 the posterior ones; and it moves in a lateral direction with 

 almost as much ease and expedition as it does straight 

 forward. The largest individuals of this species observed 

 to be conveyed through the atmosphere by a current of 

 air acting upon their lines, measured one-sixth of an inch 

 between the extreme points of the head and abdomen; one- 

 tenth of an inch across the broadest part of the abdomen; 

 and weighed about a quarter of a grain. 



The second species has also four eyes of a greater magni- 

 tude than the other four. The arrangement and relative 

 size of three pair placed in the fore-part of the head may 

 be thus expressed by dots :..: ; one of the other pair of 

 large eyes being situated on each side of the head. Spi- 

 ders of this species have the last pair of legs longer than 

 the first, and move with great celerity, but rarely in a 

 lateral direction. They vary considerably in colour, some 

 being of a much darker hue than others, and these are fre- 

 quently without the pale longitudinal line which extends 

 the whole length of the thorax, and sometimes even on 

 to the abdomen of the lighter-coloured specimens. The 

 largest individuals seen floating in the air were somewhat 

 inferior in weight and dimensions to the largest of the pre- 

 ceding species observed under similar circumstances*. 



Trans. Linn. Soc. 



* Is this llie Avanea dorsaiis of the Siistema Nitturte, Gmelin's Edit.? 



FOUNTAIN TREES. 



The Fountain Trees are very extraordinary vegeta- 

 bles, growing in one of the Canary Islands, and likewise 

 said to exist in some other places. Of these remarkable 

 trees, we have the following account in Glasse's History of 

 the Canary Islands: " There are only three fountains of 

 water in the whole island of Hiero, where the Fountain 

 Tree grows. The great cattle are watered at those foun- 

 tains, and at a place where water distils from the leaves of 



