545 



LUMME. 



LUNGS. 



546 



Decaying animal bodies frequently emit a Itimiuous appearance, 

 which has generally been attributed to the presence of phosphate of 

 lime in their skeletons, which become decomposed and yield phosphorus 

 when exposed to the action of organic compounds in a state of 

 decomposition. It is to this cause that the luminosity of putrefying 

 fish is attributed. But the emission of light is a very constant 

 phenomenon of many of the invertebrate animals under peculiar 

 circumstances. Thus during warm weather, when a vessel passes 

 through the ocean, the waves frequently exhibit a diffused lustre 

 with here and there streaks and stars of a brighter light. This occurs 

 in our own climate, but the phosphorescence is much more brilliant 

 in tropical seas. Poppig, in hia ' Reise in Chili, Peru, und auf dem 

 Amazonstrome,' describes this phenomenon in an equatorial sea. 

 " Whilst one side of the vessel is still illuminated tiy the last fading 

 rays of the evening sun, and the opposite side darkened by the shade 

 of the sails, the sea in this direction already becomes brilliant. One 

 spot after another begins to be illuminated, indistinct stripes of light 

 commence glimmering from greater depths, till at last, with the 

 approach of night, a new creation seems to be called into existence. 

 These illuminated beings move in various directions, sometimes 

 appearing like sparks, sometimes like a radiating ball of fire, at others 

 darting through the dark surface of the water like a rapid flash of 

 lightning. A great number of these beings are undoubtedly true 

 night animals which conceal themselves during daylight in the dark 

 depths of the ocean." 



These lights in the sea are principally produced by various species 

 of the family Acalephce, or Jelly-Fishes. [ACALEPHA;.] The light emitted 

 by these animals seems to be due to the secretions on the surface of 

 their bodies, for when this secretion is removed it retains for some 

 hours its luminous character, and will even impart it to milk or water. 

 But this property is not confined to the Acalephai; many species of 

 Polypi/era, some of the Echinodermata, and the lower forms of 

 Molluica also exhibit this appearance. Some few of the Crustacea 

 and even Fishes have been observed to possess the same property. 



Amongst insects this phenomenon is not uncommon. Those which 

 possess the greatest luminous power belong to the Coleoptera, the 

 Beetle-Tribe, and of these the two families represented by the Fire- 

 Fly the Elateridce, and the Glow- Worm the Lampyrida:, are the 

 most distinguished. [ELATERID.E ; LAMPYRID*:.] Some of the species 

 of the tribes of Myriapoda and Annelida give out light occasionally, 

 as the Centipede and the common Earth-Worm. 



(Meyen, Pjlanzen-Phyiiolcgie, Band ii. ; Carpenter, Animal Physi- 

 ology; Lankester, in Gardener's Chronicle, 1843). 



LUMME, a name for the bird called the Speckled Diver, or Speckled 

 Loon (Colymbia Arcticus, Linn.). [COLYMBID.E.] 



LUMP-SUCKER. [DISCOBOLI.] 



LUNGS, the organs of respiration in the higher animals. In man, 

 whose lungs may be taken as a type of those of all Mammalia, they 

 are thus formed : The trachea, or windpipe, is a rounded tube 

 continued from the larynx [LARYNX], and commencing about an inch 

 above the upper edge of the breast-bone. Its front and sides are 

 chiefly composed of portions of cartilage forming about three-fourths 

 of rings an eighth of an inch wide ; and its back' part consists of trans- 

 verse and longitudinal fibres of elastic (and, according to some, 

 muscular) tissue. The rings are connected by tough cellular and 

 elastic tissues, and by numerous strong longitudinal bands ; and the 

 whole tube, as well as its farthest ramifications, is lined by a mucous 

 membrane continued from the larynx, and covered on its free surface 

 by a fine epithelium composed of cells with vibrating cilia; attached to 

 tbern. [CILIA.] 



The trachea divides into two main branches, the bronchi, one of 

 which goes to each lung, and in it divides into smaller and smaller 

 branches, whose structure is in all essential respects similar to that of 

 the trachea. (Fig. 1.) Around the extremity of each of the finest 

 branches of the bronchial tubes there are arranged a number of delicate 

 rounded cells or vesicles, all opening into the end of the branch, but 

 having no communication with each other. On the walls of these 

 cell* the blood circulates in the minutest capillary divisions of the 

 pulmonary artery and veins, and it is also in these cells that the air, 

 which is admitted to them through the bronchial tubes, comes nearly 

 into contact with the blood. For the mode in which the blood is 

 conveyed to the lungs see the article HEART. The pulmonary artery 

 arising from the right ventricle carries to the lungs all the blood that 

 has been circulating through the body ; one main branch goes to each 

 lung, and, accompanying the bronchus, divides, like it, to extreme 

 minuteness. At the last its branches terminate in the capillaries, 

 which are arranged in the most delicate network on the walls of every 

 pulmonary cell. Each of these cells is about ^ of an inch in diameter; 

 the capillary vessels are about 7 r>'so f "" ''"''' '" diameter; and the 

 network which they form is so close that its meshes are not more 

 than irtan of a " inch wide. In its passage through these the blood 

 undergoes the changes which convert it from venous to arterial, and 

 render it again fit for the maintenance of life. [BLOOD.] From the 

 capillaries it passes into the pulmonary veins, and through them to 

 the left side of the heart. 



Kiilliker in his 'Manual of Human Histology' gives the following 

 account of the bloodvessels of the lungs: "They occupy," he says, 

 " a unique position, inasmuch as they possess two complete vascular 



NAT. HIBT. D1V. VOL. III. 



I, larynx; 2, .trachea; 3, right hronchus ; 4, left bronchus; 5, left lung, 

 the fissures denoted by the two lines which meet at C, dividing it into two lobes, 

 and the smaller lines on its surface marking the division of the lobes into 

 lobules ; 7, large bronchial tubes ; 8, minute brcnchinl tubes terminating in the 

 air-cells or vesicles. 



systems for the most part distinct from each other that of the bron- 

 chial vessels, for the nutrition of certain portions, and that of the 

 pulmonary vessels for the fulfilment of their proper function. The 

 branches of the pulmonary artery follow pretty nearly the course of 

 the bronchial tubes, which are most usually placed below and behind 

 them, with this difference, that they divide dichotomously with greater 

 frequency, and consequently diminish more rapidly in diameter. 

 Ultimately a twig goes to each secondary lobule, which then subdi- 

 vides into still finer ramuscles, in general corresponding in number 

 with the smallest lobules, and supplying the individual air-cells. 

 The course of these finest lobular arteries, as they may be termed, is 

 very easily traced in injected, inflated, and dried preparations ; and it 

 is apparent that, whilst traversing the uniting tissue between the 

 lobules (infundibula), they supply not one lobule alone, but always 

 two, or even three of them with finer twigs. These penetrate from 

 without, upon, and between the air-cells, divide repeatedly while 

 running in the larger elastic trabeculae, anastomosing also occasionally, 

 though not regularly with each other, or with branches of other lobular 

 arteries, and finally terminate in the capillary plexus of the air-cells. 

 This plexus, which is one of the closest existing in man, as estimated 

 in moist preparations, presents rounded or oval meshes 0'002"' O'OOS''' 

 wide, and vessels of 0-003"' O'OOS'" in diameter. It lies in the wall 

 of the air-cells at a distance of about O'OOl'" from the epithelium, in 

 the middle of the fibrous tissue, and is continuous, not only over all 

 the alveolae of one of the smallest lobules, but also, at all events in the 

 adult, is partially iu connection with the plexuses of the contiguous 

 lobules. The pulmonary veins arise from the above described capillary 

 plexus, with roots which lie more superficial than the arteries, and 

 more externally. On the smallest lobules these run deeply between 

 them and unite with other lobular veins into larger trunks, which 

 proceed in part with the arteries and bronchial tubes, in part more 

 isolated by themselves, through the pulmonary parenchyma. 



"The bronchial arteries are distributed, firstly, to the greater 

 brouchiso, whose vessels present the same conditions as those of the 

 trachea, then to the pulmonary veins and arteries, the latter of which 

 in particular possess an extremely rich vascular plexus, which may be 

 traced as far as branches of "' and less ; lastly, to the pleura pulmo- 

 nalis, the branches destined for which are some of them given off 

 even at the hilus and in the fissures between the main lobes, some 

 also from the vessels accompanying the bronchia) coming out between 

 the secondary lobules. Small vessels moreover which are not derived 

 from the bronchial arteries pass on the pulmonary ligaments to the 

 pleura." 



The lungs are thus mainly composed of air-cells and of branches of 

 the pulmonary artery and veins. Each lung is divided into two or 

 three large portions called lobes (the right lung has almost always 

 three lobes, the left two lobes), each of which receives one of the 

 main divisions of the bronchus, artery, and vein ; and these are 

 again divided into lobules, the outlines of some of which are marked 

 by the angular figures on the surface of the lung. Lastly, the cells 

 are grouped together in still smaller lobules not more than a quarter 

 of an inch in diameter. 



The lungs are placed in the two principal cavities of the chest. The 

 annexed figure (fiy. 2) represents the bony frame-work of the chest, 

 bounded behind by the spine and the ribs as far outwards as their 

 angles, in front by the sternum, or breast-bone, and the cartilages of 

 the ribs, and on each side by the bodies of the twelve ribs. The space 

 which is left below in the skeleton is, in the entire subject, filled up 



2 N 



