1SONANDRA. 



ISOPODA. 



ttsi paint are small cases, which an situated in the angle* formed by 

 Ik* union of the Uares and the contracted utem ; those seated in tho 

 axilla of UM outer or inferior leaves are dirided into three cavities, 

 tn-tatumy about fifty spherical bodies (granule*); the can* in the 

 axilla of the internal or tuperior leare* are dirided by numerou* 

 tnmrene partition* into many cavities, all of which are filled with 

 an impalpably fine powder, in the early stages of it* development 

 white, bat subsequently breaming black. 



Tb* pecio* of Itoetrt grow at the bottom* of pond* and lakes, and 

 are said to afford excellent food for nib. They are called Quillwort* 

 from the null or quill-like appearance of the leave*. 



/. lacntlrit, Quillwort, ha* subulate rnundUh-quftdranguUr leave* 

 with fuur longitudinal jointed tube*. The rhizoma of thia plant is a 

 blunt tuber ; the leave* are (Under, broad, and fiat at the base, but 

 elsewhere between cylindrical and quadrangular. It is found in Great 

 Britain at the bottom of lake* and pond* in hilly district*. The 

 tructure of the fructification of thi* plant, and other species of tho 

 genus, u only imperfectly understood. It is on this account referred 

 to Hamilton* by tome author*, and made to form an independent 

 order by other*. Lindley refer* it to Lycopodiacta, and observe*, 

 " I follow D* Candolle and Brongniart in referring it here." Delilehaa 

 published an account of the get initiation of Iwtttt tttacta, from which 

 it appear* that iU aporule* sprout upward* and downward*, forming 

 aa intermediate tolid body, which ultimately become* the stem or 

 cormiu, but it U not stated whether the point* from which the 

 ssesniliii* and descending axe* take their rise are uniform ; aa no 

 analogy in structure i* discoverable between these iporule* and seed*, 

 it i* probable that they are not Delile point* out the great affinity that 

 arista between Itotla and Lytopodium, particularly in the relative 

 position of the two kind* of reproductive matter. " lu Lycopodium," 

 be says, " the pulverulent theca occupy the upper end* of the shoots, 

 and the granular theca: the lower part* ; while in Itotla the former 

 are found in the centre and the latter at the circumference. If this 

 companion i* good, it will afford some evidence of the identity of 

 nature of those threw, and that the pulverulent one* are at least not 

 sathers, as ha* been supposed; for in Itotla the pulverulent inner 

 theca hare the same organisation, even to the presence of what has 

 been called their stigma, a* the outer granular ones; so that if 

 /toriti ha* sexes, it will offer the singular fact of ita anther having a 



n, Manual of BritUk Botany ; Newman, i/ittory of Britith 

 Ptrmt ; I jndler, \alural SfUfm ; Burnett, Outlintt of Botany.) 



ISONAM'KA, a genus of Plants belonging to the natural order 

 Sapotamr. It is distinguished by the stamen* being all fertile, and 

 twice a* numerous a* the lobe* of the corolla. 



/. 'i-nia (Hooker), the Gutta-Percha Tree, ha* it* leave* on long 

 (talks, oborate-oblong, with a abort point golden beneath ; flowers 

 axillary, fascicled ; stamen* 12. Thi* tree i* a native of the Malayan 



yielded by thi* tree, and designated by the name of 

 GutU Percha (pronounced ' Pertaha '), is, like Caoutchouc, a carburet 

 of hydrogen, and iaomerio with that substance, and possesses a great 

 Dumber of the properties v/hich characterise India Rubber [INDIA- 

 RrsBEK], but exhibit* certain special properties which admit of it* 

 being applied to particular uses to which caoutchouc i* not adapted. 

 Ontta-Perrna possesses a* great an indestructibility by mean* of 

 chssatcal agents as caoutchouc. It has an intermediate consistence 

 between that of leather and wood ; it is capable of being softened by 

 heat, and of regaining its primitive conscience on cooling. It is 

 therefore at the same time capable of taking and of retaining the most 

 delicate impression*. The important use* to which it has been latterly 

 applied are only the forerunners of those to which it will be adapted 

 hereafter, provided the lack of this precious material (which unfortu- 

 nately is produced in much less quantities than India-Itubber, and in 

 localities touch more circumscribed) does not present an obstacle 

 to it. 



Whilst the plants which furnish caoutchouc abound in the whole of 

 the territorial tone which extends between the tropic*, the Im<in<lra 

 Omlto ii the only tree which yields (iutta Percha. It grow* scarcely 

 anywhere exorpt in certain part* of the Malayan Archipelago, and up 

 to the present tin* has been almost exclusively obtained from 

 BisgBpon. It was brought for the first time into England in the 

 days of Tradsscant, a* a curious product, under the namo of Mazer- 

 Wood ; sad subsequently it was frequently brought fn-m China and 

 other |rta of the East, under the name of India -Rubber, in the form 

 of elastic whip*, sticks, Ac. In IMS Doctors D' Almeida and W. 

 Montgomery drew particular attention to it, together with its various 

 bsrahr properties, its easy manipulation, and the use* for which the 

 Malays emplnynl it. The most common employment of it was for 

 whip* ; and it was by the introduction of a bone-whip made of this 

 Mbeteace that its existence was for the first time known in Europe. 

 The ptcimens of the products of the Kat Indies, shown in the Great 

 Exhibition of IBS], proved that the native* of the country in which 

 the /. Omila grow, know also bow to appropriate it to the manufacture 

 of different kinds of vases, and that European industry has little more 

 to do than to imitate their promisss. 



The importation of Gutta- Percha into England, where the employ- 

 t of this substance first drew attention, was in 1845 only 20,800 Ibs. ; 



but in 1S48 it had increased to above 3,000,000 Ibs. ; and during the 

 last five yean the importation has amounted to a much Urger 

 quantity, and one which begin* to cause some apprehension as to the 

 possibility of tho supply sufficing for the requiromi-nt "I" tin- novel 

 use* in store for it in the future. It U true that during it* use GutU- 

 1'ercha is but little cou*umed, and the waste from the articles in this 

 material, submitted to a proper softening, can be made to serve new 

 uses ; nevertheless its constantly increasing consumption, added to the 

 barbarous manner in which the product ha* hitherto been extracted, 

 may well justify some apprehension. 



During the first few yean of the employment of Gutta-Percha it 

 was the custom to cut down the tree for the purpose of obtaining tlit> 

 juice, which, left to itself, very soon allowed the Gutta-Percha to 

 separate and coagulate of its own accord. There is reason to hopo 

 that European industry will soon be embarked in the cultivation of 

 thi* product, and that the Niato (which i* the name that the Malay* 

 give to the tree which produces Gutta-Percha), multiplied by means 

 of a regular culture, naturalised in other countries than those to 

 which it is indigenous, and worked by regular incisions, which will 

 only take from the tree a portion of ita juice without hindering its 

 development, will be the means of furnishing nt a low price a sub- 

 stance which is destined to render notable services to industrial and 

 domestic economy. 



The Gutta-Percha which arrives in Europe in the form of lumps 

 of some pounds weight is far from being pure. The natives of tho 

 Malayan Archipelago make no scruple of introducing into it stones, 

 earth, &c. ; the presence of which in the interior of these blocks 

 renders a purification indispensable, which purification however is 

 capable of being attained without much manipulation. 



Indestructible by water, and at the same time a bad conductor of 

 electricity, (Juttu- Percha has been fouud available for inclosing the 

 metallic wires employed in the electric telegraph ; and the use of this 

 substance may certainly claim its share in the success of the submarine 

 telegraph, by mean* of which London and Paris and the other great 

 cities of Europe are now brought within a few minutes of each other. 



It may be conceived to what a variety of forms a substance can be 

 turned which, becoming soft without adhering at the temperature 

 of boiling water, regain* at the ordinary temperature tho slight 

 elasticity and the consistence of leather. [GUTTA-PERCHA, in ARTS 

 AND Sc. Drv.] 



ISO'PODA, Latreille's name for the fifth order of the class Oruttaetn. 

 The hopoda, accordiug to that zoologist, approach the Lamodipoda 

 by the absence of maudibular palpi, though they are removed from 

 them by several points; the two anterior feet are not annexed to the 

 head, and, like the succeeding ones, depend upon their particular 

 segment. The feet are always fourteen in number, unguiculated, and 

 without any vesicular appendage at their base. The under part of 

 the tail is furnished with appendages which are very apparent, and 

 in the form of leaflets or vesicular purses. Of these the two first, or 

 external ones, ordinarily cover the others, either totally or in great 

 part The body U generally flattened, and wider than it is thick. 

 The mouth is composed of the same pieces as in the Criutacta, which 

 precede it in M. Latreille's system, but in the order before u* those 

 which answer to the two superior jaw-feet iu the Decapoda present 

 more the appearance of a lower lip terminated by two palpi. Two of 

 the antenna:, the mesial ones, are almost obliterated in the last genera 

 of this order, which are all terrestrial, and differ besides from the 

 other by their respiratory organs. The male sexual organs are 

 indicated most frequently by the presence of linear or filiform appen- 

 dages, and sometimes by hooks placed at the internal origin of the 

 first subcaudal latniux. The females carry their eggs under the breast, 

 either between the scales or in a membranous pouch or sac that opens 

 to afford a passage for their young, which are hatched with the form 

 and parts propur to the species, and only cast their skin aa they 

 increase in size. The greater number live in the water. Those which 

 are terrestrial have need, like other Crustacea that live out of water, 

 of a certain degree of atmospheric humidity, in order that respiration 

 may be carried on, and that their bronchia; may be in a fit state for 

 performing this function. 



Mcstrs. Victor Audouin and Millie-Edwards have studied very care- 

 fully the organisation of the /<m]to<la, the Liyiir e[>ecially. It appear* 

 from their observations that tho heart has tho form of a long vessel 

 extended above the dorsal surface of the int. -tine. Its anterior 

 extremity gives off three arteries, as iu the Decapoda, The lateral 

 branchial may also be seen directed from the heart towards the feet. 

 At the edge of the two first articulations of the abdomen, or tail, 

 this organ receives, both right and left, small canals (the brauchio- 

 cardiac vessel*), which seem to come from the branchial. According 

 to the demonstration* of these zoologists in the case of the l.igite, it 

 would appear that the venous system is less complete than in the 

 Macrurous Decapoda ; and that the blood driven from the heart to 

 the different parts of the body passes into lacuna), which the organs 

 leave between them at the lower surface of the body, aii'l which 

 have a free communication with the different vessels of the bronchia:. 

 The blood, after having traversed the respiratory apparatus, returns 

 to the heart in traversing the branchio-cardiacal vessels. This dispo- 

 sition would establish the passage from the circulating system of the 

 Decapodous Cruttacta to that of tho Branchiopoda. Accordiug to 



