REPTILES. 



Nouvelles Obf. fur la Vipere, p. 39. Tyfon in Phil. 

 Trani. N° 144. p. 30. tab. I. fig. I. tab. 2. lig. 4. Scha 

 Tln.-faur. vol. ii. tab. 109. fig. 1 — 5.) TIic pulmonary 

 bag of tliis coluber exceeds a Paris foot in length. Rather 

 more than the anterior half has thick fides, witn an elegantly 

 reticulated internal furfacc, rcfembling in its general habit 

 that of the internal furface of the fecond ilomach of the ru- 

 minating mainmaha. The remaining pollerior portion is a 

 fimple thin membranous bladder." Specimen, p. 12. 



The Itrufture is rather more complicated in the chelonian 

 order. Each of the openings of the bronchus, which we 



pafs back again tln-ough the lungs to return to the body : 

 It may proceed by another route, as we have explained in 

 the account of the circulating organs ; becaufe it does not 

 require to be fo frequently fubmitted to the adtion of the 

 air, as in the two clalfes mentioned above. Hence liavc re- 

 fulted the two great differences already ponited out be- 

 tween the lung.s of the warm-blooded clailes and of reptiles ; 

 differences which are obvioufly related to each other, the 

 numerous vafcular ramifications requiring numerous cells 

 and vifcera. 



Tlie pulmonary ferve alfo as bronchial velicls in reptiles ; 

 have ftated to be about ten or twelve in the teftudo grxca, at leatt we lind no arteries or veins of the latter defcription! 

 is the entrance of a particular fac, the fides of which are The arterial and venous bloods are mixed in the heart ; and 



the farac that goes to the lungs is conveyed to all other 



compofed of polygonal cells, in which there arc (lill fmaller 

 ones. Each of ihefe cells is bordered by whilifli and as it 

 were tendinous chords, which appear dcfigned to fnpport 

 their fides, and fix the facs to the orifices of the bronchus. 

 The facs or principal cells are much fmaller, and more nu- 

 merous, in the turtles, and correfpond to the numerous ori- 

 fices with which the bronchus is pierced. We fee alfo the 

 cords forming and fupporting the cells, and giving to the 

 lungs of thofe animals the appearance of a cavernous tidue. 



The form and fize of the pulmonary cells may be fomc- 

 what different in the crocodile, but their eifential Itrufture 

 is the fame. In this refpeft the crocodiles depart from the 

 lizards, and a])proach the turtle and tortoife. Geoffroy in 

 Annales du Mufeum, vol. ii. p. 46 



parts of the body for their fupply. 



Yet the pulmonary are not the only arteries conveying 

 blood to the lungs in reptiles : the ferpents, at lealt, offer 

 an exception. The ramifications of the pulmonary artery 

 are confined to that part of the lung, which has a reticu- 

 lated internal furface. The poflerior part of the organ, 

 compofing the fimple membranous bag, receives blood only 

 from the arteries of the body. A part of the twigs that 

 fupply it comes from the branches of the pofterior aorta, 

 which are alfo diftributed on the ftomach. Other very mi- 

 nute ones are detached fucceflively from the vertebral co- 

 lumn. The veins correfponding to thefe arteries pour their 

 blood into the vena cava. In tlii; fiiignlar ilrudure, we 



How different a notion do thefe details convey to us, of find a part of the lung executing the office of the cells of 

 the llruiture of the lungs in reptiles, from that which they birds ; and a portion of the blood, very fmall indeed, con- 



poffefs in the warm-blooded claffes ! Although they may tained in the arteries of the body, is again fubmitted to the 



be defcribcd in the latter as cellular, fpongy, and light, adtion of the air. 



yet, when compared to the fame organs in the former clafs. That portion of the general ferous membrane which co- 



they are valUy more compadl, made up throughout of an in- vers the lung has nothing peculiar in reptiles, 

 finite number of ramified air-tubes, and of countlefs moft Tiie form and bulk of the organs vary much more in this 



minute bronchial cells connedlcd to them, united and inter- clafs, than in the mammalia and birds. Both are determined 



woven v^'ith common cellular tiffue. Hence, if we compare in the mammaha by the cavity of the thorax ; in birds by 



any mammiferous animal with a reptile of the fame fize, as the peritoneal cells, which limit them on one fide, and bv the 



the vefpertilio murinus with the rana bombina, the lungs of ribs, which cover them on the other. In reptiles, on the 



the latter are indeed the largell, but are beyond all com- contrary, nothing feems to limit their developement, nor to 



parifon inferior to thofe of the former in the very incon- give them a peculiar figure. Commonly they form oval ba^s 



fiderable number of their cells. which extend in the chelonians along the back to the pelvit. 



As the lungs of warm-blooded animals fo wonderfully above all the vifcera ; they are lefs extenfive in the faurians 

 furpafs thofe of reptiles, in the minutenefs and number of and batracians. The ferpents have a fingle very long lun?, 

 their cells ; fo they ftill farther excel them in the aitonifhing prolonged over the cefophagus, ilomach, and liver, beyond 

 abundance of their blood-veffels. The fimple appearance the latter parts. In this fitnation it is expofed to preffure 

 of the organs, without any anatomical preparation, is fuffi- every time the animal fwallovvs a large prey. Does this 

 cient to fliew this faft ; and microfcopical examination, check the pulmonary circulation, and contribute to the tor- 

 after fuccefsful injedlion, fully confinns it. For, although por which ferpents experience at thefe times ? 

 the lungs of the amphibia exhibit their der.ie vaicular net- In the cameleon, and the agame marmorata, each pulmo- 

 works, beautifully painting the fides of the cells, thefe are nary fac is very extenfive. They are divided into large co- 

 not to be compared to the number and fubtilty of the rami- nical appendices, prolonged as far as the pelvis, placed 

 fications, eluding even the afBfted eye, which every where among the vifcera, and capable of holding fo much air, as 

 fill up the lungs of warm-blooded animals. to increafe the animals' bulk confiderably when they are dif- 



Since, in the mammaha and birds, all the blood of the tended. The lungs of the firen lacertina aretwolonu- cylin- 



body muft pafs through the lungs, before it can return 

 again to the organs, it was neceflary to have a large num- 

 ber of veffels for its conveyance, and a furface for their 

 expanfion, both extenfive on account of their number, and 



drical facs, continued to the end of the abdominal cavity. 

 In the larvE of the falamander, there is a (mail oval cavity, 

 opening by a narrow canal in the fauces. 



Branchia or GUIs. —The firft orders of reptiles (the chelo- 



the neceffity of expofing the blood in minute portions to the nians, faurians, and ophidians) never poffefs this kind of refpi 

 air, and yet confined as much as poffible to one fpot, that ratory organ : they have only lungs. The batracians in 



its bulk might not be inconvenient. Thus we explain that 

 inextricable tii'lue of blood and air-veffels, and fmall veficles 

 or cells, which compofe the lungs of mammalia and birds. 

 All thefe circumftances are different in reptiles. If we may 

 judge from the diameter of the pulmonary arteries, they re- 

 ceive at moft a third of the circulating mafs, and fome- 



their firll ilate, and the proteus and firen during life, have" 

 both lungs and branchis, or rather branchial appendages 

 (appendices fimbriati). See the anatomy of the tadpole, 

 and that of the proteus and firen, at the end of this ar- 

 ticle. 



Expanfi-ve Ponver of the Lungs. — " A fingular power," 



times much lefs. It is not necefl'ary that this blood ftould fays Bluraenbach, « charadterifes thefe vifcera in reptiles, and 



