325 



DIANDRIA. 



DIASPORE. 



326 



subjoined cut will convey to the reader the form of one of the so- 

 called species. 



Dianchora striata. 



Four species of this genus have been found in the Chalk and Green- 

 Band : D. lata, Sowerby ; D. obliqua, Mantell ; D. alriata, Sowerby ; 

 D. truncata, Lamarck. 



DIA'NDRIA, the second class in the Linntean system of arranging 

 plants. It comprehends all genera with flowers having only two 

 stamens, provided the stamens are neither united at their base, nor 

 combined with the style and stigma, nor separated from the pistil 



DIANTHUS, a beautiful genus of Silenaceous Dicotyledonous 

 Plants, with a calyx closely covered at the base by two, three, or 

 four opposite pairs of decussating rigid sharp-pointed bracts. The 

 petals are always more or less lacerated at the end, and in some 

 species are divided into fine capillary segments. There are 10 sta- 

 mens, 2 styles, and the capsule is 1-celled, with numerous black seeds 

 containing a straight embryo. In all cases the leaves are long, narrow, 

 1-ribbed, sharp-pointed, and destitute of all lateral reticulated veining. 



De Candolle enumerates 113 species, of which some must undoubt- 

 edly be reduced to simple varieties. They are found in all the tem- 

 perate parts of Europe and Asia, from Ireland to the eastern coast 

 of China and Japan ; two have been met with in the United States of 

 America, and four at the Cape of Good Hope. Most of them are 

 perennial herbaceous plants with permanent leaves and stems, and 

 hence they ought perhaps to be considered under-shrubs ; a few 

 become woody and form genuine bushes. 



D. barbatui, the Bearded Pink or Sweet William, has aggregate 

 flowers in bundles ; calycine scales ovate, awl-shaped, equal in length 

 to the tube ; the petals bearded ; leaves lanceolate and nerved. It 

 is a native of the south of France and Germany, in gravelly or sandy 

 places. The flowers are very variable in colour, from dark purple to 

 white, or variegated or speckled, single and double. Sweet William is 

 a very favourite and old-fashioned inhabitant of the garden, and was 

 much esteemed in the time of Gerarde for its beauty. 



D. Caryophyllut, the Carnation, is a native of the south of France, 

 and in England on old walls in Kent and Norfolk. It has solitary 

 flowers ; the calyx-scales broadly obovate, pointed, four times shorter 

 than the tube ; the leaves with smooth linear margins ; the petals 

 crenate, dentate, ovate, glabrous ; the stem barren, elongated, pro- 

 cumbent, branching; the seeds pyriform, nearly flat; the flower- 

 stems are from 12 to 18 inches high ; the calyx-teeth not ciliated, 

 longer than the capsule. The flowers are of all colours, excepting 

 blue : in the British species they are of a pale pink, and in all cases 

 fragrant. The flowers of the variety of this species, known as the 

 Clove-Pink, are used to give a colour and fragrance to an officinal 

 syrup used in pharmacy. A small variety of the species is known by 

 the name of Picotees. 



D. plumariut is the type of the Common Garden-Pink. It is a 

 native of Europe, and is found in England on old walls and ruins. 

 It has solitary flowers, two or three on a stem ; the calyx-scales are 

 roundish-ovate, shortly mucronate, four times shorter than the tube ; 

 the leaves rough at the margin, linear, subulate ; the petals digitate, 

 multifid as far as the middle, with the central entire part obovate, 

 downy ; the stem barren, procumbent, rooting, much-branched ; the 

 seeds flat, orbicular, with a point on one side ; the flowering stems are 

 from 6 to 12 inches high; the calyx-teeth are ciliated at the margin, 

 slightly shorter than the capsule. The flowers are either double or 

 single, white, pink, spotted, or variegated, and sweet-scented. 



Of the specie* of this genus six are British, and are described by 

 Mr. Babington in his ' Manual of British Botany.' 



For the cultivation of the Carnation, Pink, &c., see PINK, in, ABTS 

 AND Sr. Div. 



DIAPENSIA'CE-iE, Diaperuiadt, a very small natural order of 

 Monopetalous Exogenous Plants, formerly referred to Convolvulacea, 

 but in reality are more nearly allied to Loganiacece and Stilbacetf, 

 Only two genera, Diapcnria and Pyxidanthera, are known; they 

 consist of small depressed half-shrubby species, with the habit of a 

 minute-leaved Phlox. Their calyx grows in a broken whorl; the 

 corolla has an imbricated (estivation with five lobes, and as many 

 stamens growing from its margin in the sinuses ; the anthers have a 

 broad connective, and burst transversely ; the ovary is 3-celled, with a 

 good many ovules growing upon central placentae ; finally, the embryo 



lies across the hilum, iu the midst of fleshy albumen. No use has 

 hitherto been made of these plants. (Liudley, Vegetable Kinydom.) 



DIAPHRAGM (Aicufifay/ia), Septum Transveraum, Transverse Parti- 

 tion, Midriff, a circular Muscle, placed between the thorax and 

 abdomen, forming a moveable partition between these two great 

 cavities. Its borders, which are broad and fleshy, are moveable ; its 

 central portion, which is tendinous, is fixed and immoveable. When 

 not in action, its upper surface, or that towards the thorax, is convex, 

 presents the appearance of an arch, which reaches as high as the 

 fourth rib, and is covered by the pleura, the membrane which lines 

 the cavity of the thorax. Its under surface, or that towards the 

 abdomen, is concave, and is covered by the peritoneum, the mem- 

 brane which lines the cavity of the abdomen. It is perforated by 

 several apertures, through which important organs pass from the 

 thorax into the abdomen, and from the abdomen into the thorax. In 

 its tendinous portion, between what is called its crura, or legs, there 

 is an oval aperture through which the aorta, or great artery of the 

 trunk, passes from the thorax into the abdomen, and the thoracic duct 

 enters from the abdomen into the thorax. A little above this and to 

 the left of it, in the fleshy portion of the diaphragm, is an aperture 

 through which the oesophagus passes in its course from the mouth to 

 the stomach. On the right side of the diaphragm, in its tendinous 

 portion, is a third aperture, through which the inferior vena cava 

 passes from the abdomen to the heart. 



The diaphragm is a muscle of extreme complexity in its structure, 

 and next to the heart performs the most important function of any 

 muscle in the body. Its most important office is connected with the 

 function of respiration, and it is the principal agent both in enlarging 

 the cavity of the thorax in inspiration and in diminishing it in expi- 

 ration. These actions it performs by virtue of the power of alternate 

 contraction and relaxation which it possesses in common with all 

 muscles. When in the state of relaxation, as in expiration, its broad 

 lateral moveable borders present an expanded arch, the convexity of 

 which reaches, as has been stated, as high as the fourth rib ; when in 

 action, as in the state of inspiration, the fibres composing the lateral 

 borders contract, whence this moveable partition descends, until from 

 the form of an arch it presents a plane surface, increasing the capacity 

 of the thorax by all the space that intervenes between the fourth rib 

 and the lowest point to which the diaphragm is capable of descending. 

 The fibres then relaxing, the moveable borders are pushed up by the 

 contraction of the powerful muscles of the abdomen, until the dia- 

 phragm again assumes the form of an arch, diminishing the capacity 

 of the thorax by all the space that intervenes between the lowest 

 point to which it descends and the fourth rib. These alternate 

 actions, which are performed in regular and uninterrupted succession, 

 day and night, during our sleeping and our waking hours, from the 

 moment of birth to that of death, constitute the principal portion of 

 the mechanical part of the function of respiration or breathing, by 

 which air and blood flow to and from the lungs. During these 

 actions the central portion of the diaphragm, ou which the heart 

 rests, and to which the pericardium is attached, never moves ; so that 

 though the diaphragm is in constant motion it never disturbs the 

 action of the heart, which it assists in supporting, and the function 

 of the circulation is not disordered by the movements which are 

 indispensable to the function of respiration. 



There is a fixed relation between the action of the diaphragm and 

 of the abdominal muscles. When the diaphragm contracts the 

 abdominal muscles relax ; when the abdominal muscles relax the 

 diaphragm contracts. The diaphragm is the antagonist of the abdo- 

 minal muscles in inspiration ; but it acts in concert with them in 

 vomiting, in the discharge of the contents of the bowels and of the 

 urinary bladder, and in assisting the expulsion of the foetus in partu- 

 rition. To produce the respiratory movements, and to assist in the 

 expulsion of the faeces, the urine, and the foetus, may be considered 

 the natural and regular offices of the diaphragm ; but it conduces to 

 the performance of many other actions. It is_ the principal agent in 

 vomiting, yawning, coughing, laughing, crying, and in hiccup, which 

 may be regarded as its more powerful and irregular actions. 



For diagrams representing the position of the diaphragm and its 

 relation to the other organs of the body, see ABDOMEN and HEART. 



DIASPORE, a Mineral. It is a dihydrate of alumina, and occurs 

 massive and crystallised. Its primary form is a doubly oblique prism. 

 The colour is slightly greenish-gray and yellowish-brown. Its hard- 

 ness is 6'0 to 6'5. It is slightly translucent. The specific gravity 

 is 3'43. It is found at Kosoibrod in the Orenburg government of 

 Asiatic Russia. The massive variety occurs in slightly curvilinear 

 lamime of a shining pearly lustre and greenish-gray colour ; also in 

 cellular masses, constituted of slender crystals, which have a pearly 

 lustre, and intercept each other in every direction ; of a brown hue 

 externally, but prefectly transparent and colourless when reduced to 

 thin laminse. The following is an analysis by Hess : 



Alumina ,... 85*14 



Water H'56 



The brown variety, analysed by Children, gave 



Alumina 76'06 



Water U"70 



Oxide of Iron 778 



Loss ! 



