Trachyte

“ The trachyte is of itself yellowish white; when it is stained with the black oxide of manganese and the red oxide of iron that variegates the ores, it is sure to carry silver, though this (in the form of a chloride) can rarely be seen. Sometimes, however, the silver can be seen upon the surface of a fracture in the form of a green scale, or appears in little globules of horn silver. While the rich ore is discovered in large masses, surrounded by leaner or less valuable rock, there is nowhere in the chloride belt anything that looks like a vein. ”

“ Trachurus, trā-kū′rus, n. a genus of carangoid fishes, the saurels. [Gr. trachys, rough, oura, tail.]
Trachyte, trā′kīt, n. a crystalline igneous rock, generally grayish in colour, usually fine-grained or compact, more or less markedly porphyritic, with large crystals of sanidine and scales of black mica.—adjs. Trachyt′ic; Trach′ytoid. [Gr. trachys, rough.]
Tracing, trā′sing, n. act of one who traces: act of copying by marking on thin paper the lines of a pattern placed beneath: the copy so produced.—n. ”

“ From their hardness they withstand weathering, and projecting two or three feet above the ground, they occasionally extend some yards in length; these plate-like veins, when struck, emit a sound, almost like that of a drum, and they may be distinctly seen to vibrate; their fragments, which are strewed on the ground, clatter like pieces of iron when knocked against each other. They often assume the most singular forms; I saw a pedestal of the earthy trachyte, covered by a hemispherical portion of a vein, like a great umbrella, sufficiently large to shelter two persons. ”

“ These are the normal basalts and dolerites. 2nd, A number of large dykes have a rather more acid composition and are classed as andesites. 3rd, A few dykes of trachyte have been observed in Cowal and in Skye cutting the dykes of basalt (p. 138) . 4th, In some districts large numbers of still more acid dykes occur. These are sometimes crystalline in structure (granophyre) , more frequently felsitic (felsite, spherulitic quartz-porphyry) , and often glassy (pitchstone) . In some exceptional cases the basic and acid materials are conjoined in the same dyke. ”

“ Dark brown varieties of augite and rhombic pyroxene (hypersthene or bronzite) have been observed but are not common. Apatite, zircon and magnetite are practically always present as unimportant accessory minerals.
The trachytes being very rich in potash felspar, necessarily contain considerable amounts of alkalis; in this character they approach the phonolites. Occasionally minerals of the felspathoid group, such as nepheline, sodalite and leucite, occur, and rocks of this kind are known as phonolitic trachytes. ”

“ The chief interest of this genus is that, at any rate in T. crassicauda Bel., which infests the rat, the dwarf males live two, three, or four at a time within the uterus of the female, a condition of things which recalls the similar arrangement found in the Gephyrean Bonellia.
Trichina spiralis is the cause of the well-known disease trichinosis, which appears in two forms, intestinal and muscular, according to the habitat of the parasite. The mature forms of {146}both sexes are found in the intestine of man and many other mammals. ”

“ In the male bird the trachea at the distance of about two inches above the furcula, takes an immense convolution, forming a complicated knot; the form of the turnings is not always the same, nor is their extent; I have seen one much more complicated than in the specimen dissected by Mr. Eyton, [112] and some less so. The volutions are connected by a mesentery. At the point where the bronchi divaricate, the trachea dilates into a large oval box. In the female the trachea is quite simple, having no trace of the convolution, nor of the bronchial box. ”

“ The area in Europe where trachoma is most prevalent extends from the Gulf of Finland on the north to the Black Sea and the Mediterranean on the south, and from Moscow and the Volga on the east to the Carpathian Mountains on the west. ”

“ A dry character of the respiratory murmur some time after tracheotomy indicates the approach of death within from twelve to twenty-four hours from descent of the membrane; so does cyanosis, whatever be its degree of intensity. Diphtheria of the trachea, which ascends to the larynx, is positively fatal. It has a rapid course, and tracheotomy only postpones the end for a little while, if at all. The general health and strength of the little sufferer have no influence whatever. ”

“ The trachea is 5 inches long, much flattened, its rings unossified, its diameter at the top 2 3/4 twelfths, towards the lower part 3 twelfths, having scarcely any appearance of dilatation at the part which is so excessively enlarged in the Golden-eyed Duck, which in form and habits is yet very closely allied. The lateral muscles are strong, and there are cleido-tracheal and sterno-tracheal muscles, as in other ducks. ”

“ The etiology of trachoma is unknown. Though a perfectly distinctive affection when fully established, the differential diagnosis from other forms of conjunctivitis, particularly those associated with much follicular enlargement or which have begun as purulent inflammation, may be difficult. Trachoma is mostly chronic. When occurring in an acute form it is more amenable to treatment and less likely to end in cicatricial changes. Fully half the cases of trachoma which occur are complicated by pannus, which is the name given to the affection when it has spread to the cornea. ”

“ If we examine the tracheal gills of the smaller dragon-fly (Agrion) , or the May-flies, or Sialidæ, or Perlidæ, or Phryganeidæ, we see that they are developed in a very arbitrary way, either at the end of the abdomen, or on the sternum, or from the pleurum; moreover, in structure they invariably have but a single trachea, from which minute twigs branch out; [30] in the wings there are five or six main tracheæ, which give rise to the veins. Thus, in themselves, irrespective of their position, they are not the homologues of the gills. ”

“ The arrangement of the tracheæ and stigmata is much as in insects, but in the Diplopoda the tracheary system is more primitive than in chilopods, a pair of stigmata and a pair of tracheal bundles occurring in each segment, while the bundles are not connected by anastomosing branches, branched tracheæ only occurring in the Glomeridæ. The tracheæ themselves are without spiral threads (tænidia) . It is noteworthy that the tracheæ arise much later than in insects, not appearing until the animal is hatched; in this respect the myriopods approximate Peripatus. ”

“ Fig. 400.—Tracheal end-cells of Lampyris splendidula: tr, trachea with tænidia; tre, tracheal capillaries.—After Wielowiejski.
These tracheal capillaries also occur on the seminal and other sexual tubes, on the intestine, on the urinary tubes, on the fat-bodies, but are most easily detected on the silk-glands.
The latest researches are those of E. Holmgren, who has studied the branching of the tracheæ in the spinning-glands of caterpillars. He prefers to call the end-cells “transition cells,” as they lead from the tracheal tubes proper to the capillary network. ”

“ These tubes, which are known as "tracheæ," arise as ingrowths of the outer layer of the embryo, and are lined by a delicate continuation of the external cuticle. It has been held by some zoologists that so peculiar a system of breathing organs must indicate a common descent of the animals that possess them, and accordingly it has been proposed to separate the Insects, Arachnids, Myriopods, and Peripatus, as a group, Tracheata, from the Crustacea and some other Arthropods which have no tracheæ. ”

“ Diphtheria of the larynx, whether it be of primary origin or the result of extension from the fauces, is nearly always fatal. In severe epidemics the mortality is 95 per cent. Tracheotomy, too, saves but few of those who take the disease at such a time. In fifty consecutive tracheotomies from 1872 to 1874 I did not see one recovery. In the last few years I have seen few good results. In average epidemics tracheotomy will save 20 per cent. A pulse of 140 to 160, and high fever immediately after the operation, render the prognosis bad ”

“ Tiedemann (1822) , Peacock (1828) described “little bodies” in the muscles of human cadavers which Hilton (1832) considered to be parasitic in nature. Paget (1835) showed that these bodies were round worms and Owen (1835) described them more accurately and gave the name Trichina spiralis to them. Leidy (1846) found organisms in the muscles of hogs which he considered to be the same as Owen’s Trichina and paved the way for the work of Zenker (1860) in showing the pathological relation between the Trichina of pork and human Trichinosis. ”

“ Wielowiejski, [63] in describing the line tracheæ of the phosphorescent organs, thinks that the tracheal endings (tracheal capillaries) rarely end blindly, but anastomose with one another, forming an irregular network. The latest observer, Gilson (1893) , asserts that tracheal twigs penetrate deeply into the epithelial cells of the silk glands of larval Trichoptera as well as of caterpillars, passing through their protoplasm.
Fig. 398.—Tracheal network of the male glands of Lampyris splendidula: tec, tracheal end-cells; cap, tracheal capillaries; at a, an expanded matrix.—After Wielowiejski. ”

“ The disease sometimes lasts for years without causing blindness, though it gives rise to great irritation. It is generally Trachoma.attended by a discharge, which is highly contagious, producing the same disease if it gets into other eyes. Want of cleanliness is one of the most important factors in the propagation of trachoma, hence its great prevalence in Oriental countries. Trachoma is very prevalent in Egypt, where those suffering from total or partial blindness are said to amount to 10% of the population. ”

“ Trachoma, if neglected, not only impairs the health of the eye, but may cause blindness. Tears carry the germs from the eye to the face, where they are taken up on handkerchiefs, towels, and fingers and infect other eyes. Of late, thanks to school nurses and physicians and hygiene instruction, American cities have found relatively little trachoma except among recent immigrants. So dangerous is the germ and so insidious its methods of propagation, [71] that a physician should be summoned at once at the first sign of inflammation. ”

“ But when the first alarm has quieted down, the attacks are likely to be only occasional, as when the article, drawn up with the expired air, comes in contact with the under aspect of the vocal cords. It may be that in a violent fmt of coughing it will be expelled, but, if not, the surgeon must be at hand ready to perform tracheotomy when the urgency of the symptoms demands it. Tracheotomy is the making of an opening into the trachea, the air-tube below the larynx. It is unsafe to leave a child with a foreign body loose in its windpipe, on account of the risk of sudden and fatal asphyxia. ”

“ These finest tracheal capillaries are not in Luciola filled with air, but with a colorless fluid, as was also found by Wielowiejski and others in Lampyris.
These transparent cylinders, with the tracheæ within, forming longitudinal axes, resemble lobules. These lobules are so distributed that they appear on a surface section of this plate as numerous round areas in which circular periphery the tracheal capillaries are arranged with the axially disposed tracheal end-cells. These “tracheal end-cells” are only membranous enlargements at the base of the tracheal capillaries (Wielowiejski) . ”

“ Nor was the full story of the trichina made out for a long time after Owen's discovery. It was not till 1847 that the American anatomist Dr. Joseph Leidy found the cysts of trichina in the tissues of pork; and another decade or so elapsed after that before German workers, chief among whom were Leuckart, Virchow, and Zenker, proved that the parasite gets into the human system through ingestion of infected pork, and that it causes a definite set of symptoms of disease which hitherto had been mistaken for rheumatism, typhoid fever, and other maladies. ”

“ I had myself examined the trichinised flesh taken from a dozen of these corpses, but in no instance had the faintest suspicion of trichinosis been entertained during life. The circumstances attending the only outbreak of trichiniasis that has been witnessed in England are very interesting. In the month of April, 1871, I received from Dr W. L. Dickinson, of Workington, Cumberland, specimens of pork which he requested me to examine; and in complying with his request I confirmed his opinion that the diseased meat was infested with Trichinæ. ”

“ If the body remains movable in the trachea, it is apt to be displaced when the patient moves or coughs, and it may be driven up and become impacted in the glottis, setting up violent attacks of coughing and spasmodic dyspnœa.
Tracheotomy should be performed at once, and the edges of the tracheal wound held widely open with retractors, the patient being inverted, or coughing induced by tickling the mucous membrane with a feather. The foreign body is usually expelled, but it may be inhaled into one of the bronchi. ”

“ Lubbock found a simple system of tracheæ in Smynthurus which opens by "two spiracles in the head, opposite the insertion of the antennæ," i. e., on the back of the head. (Von Olfers says that they open on the prothorax.) Nicolet and Olfers claim to have found tracheæ in several lower genera (Orchesella, Tomocerus, and Achorutes and allied genera) , but Lubbock was unable to detect them, and I may add that I have not yet been able after careful search to find them either in living specimens, or those rendered transparent by potash. ”