Gill (mycology)

“ A strong line of lateral sense-organs is formed, and a ring of them lies around the eye and others on other parts of the head. The short tail develops a fin. Of the three pairs of gills the third is the shortest, and is generally turned dorsalwards. In embryos of 4 cm. in length the longest gill measures as much as 2 cm. Yolk is still present in embryos which have reached the surprising length of 7 cm. Then the gills begin to shrink a little, and at this time one pair of gill-clefts breaks through at the base of the third external gill.
When the larvae are hatched the gills are lost. ”

“ In the 6 mm. larva the first gill shows four knobs, the second two, the third one knob. They are always delicate and thin, although sometimes pigmented, long, and much-ramified structures. The first pair is always the largest; well developed and persisting a long time in Rana temporaria; smaller in R. esculenta and Bufo vulgaris; very short, scarcely forked, in B. viridis and Hyla arborea. They are relatively largest in Alytes, while still in the egg. Numerous descriptions of these gills will be found in the systematic part. ”

“ We have already seen that the embryonic bird has the long tail of his reptilian ancestor. In early embryonic life it has gill-slits leading from the pharynx to the outside of the neck like those through which the water passes in the respiration of fish. The Eustachian tube and the canal of the external ear of man, separated only by the "drum," are nothing but such an old persistent gill-slit. No gills ever develop in these, but the great arteries run to them, and indeed to all parts of the embryo, on almost precisely the same general plan as in the adult fish. ”

“ When we look further into the matter we find that young fish also possess gill slits (fig. 10 and 11) —even in young stages in their development. Is it not then more probable that the mammal and bird possess this stage in their development simply because it has never been lost? Is not this a more reasonable view than to suppose that the gill slits of the embryos of the higher forms represent the adult gill slits of the fish that in some mysterious way have been pushed back into the embryo of the bird? ”

“ For example, there is no doubt that both birds and mammals are descended from some fish-like animal that lived in the water and breathed by gills borne on slits in the gullet, and every bird and mammal passes through a stage in which these gill-slits are present, though their function is lost, and they soon close up and disappear. ”

“ Is it not possible that these biological truths may carry with them the clue to still profounder philosophy—even that of Regeneration?
Evolutionists tell us that by the influence of environment certain aquatic animals have become adapted to a terrestrial mode of life. Breathing normally by gills, as the result and reward of a continued effort carried on from generation to generation to inspire the air of heaven direct, they have slowly acquired the lung-function. In the young organism, true to the ancestral type, the gill still persists—as in the tadpole of the common frog. ”

“ Many other rudimentary organs arise and disappear, and are explained in a similar manner. It is an astounding fact that the gill-clefts arise in all of the highest animals, without exception, and their presence is taken to indicate that the remote ancestors of all were water-breathers and had use for gills. The rudimentary organs referred to of course disappear long before the animal is hatched or born into the world. ”

“ The gill-covers and gill-rays are imperfectly developed; and are concealed under the thick skin, leaving only a small orifice for the escape of the water from the gills. The body is destitute of true scales; the skin is either hard and leathery, and scored into lozenge-shaped divisions, or covered with hard bony spines, or soft and mucous. The form is usually short and thick, sometimes quite destitute of the proportions that we are accustomed to see in other fishes, and, as it were, deformed: the fins are commonly small, and often remarkable for their position or structure ”

“ In the common case of children born with these vestiges, the old gill-slits are represented by small openings in the skin on the sides of the neck and capable of admitting a thin probe. Sometimes the place where they have been in childhood is marked throughout life by small round patches of white skin. These relics of the sea, these apparitions of the Fish, these sudden resurrections, are betrayals of man’s pedigree. Men wonder at mummy-wheat germinating after a thousand years of dormancy. ”

“ Change is apparent on every hand in the plan of nature; ages were necessary for the evolution of our present day horse from his five toed ancestors; and after all it does not seem so very startling when the transformation is enacted before our very eyes in a few short stages, as in the case of the common frog, from the gill breathing tadpole to the lung breathing adult. More startling it is to learn that man himself was at one time a gill breather, and, as biologists affirm, still exhibits traces of gill clefts at one stage of his embryonic development. ”

“ What similarities of structure do you find in nearly all of the appendages? Assuming a swimmeret of the third, fourth, or fifth somite to be the least changed from the primitive type, what changes were necessary to make the sixth swimmeret; the third maxilliped; the walking legs; the antennæ; the antennules? Remove the part of the carapace which covers a gill chamber. What are the boundaries of the chamber? Where does it open to the water? Describe the appearance and the texture of a gill. How are the gills kept moist when the crayfish is in water; when it is on land? ”

“ Upon either side of each ring is situated a singular appendage, which acts as a gill or branchial organ, by the exercise of which the blood of the animal is effectually purified, and respiration adequately provided for.
When the Nereis is in a state of repose, these gills are laid flat over its back; but in a state of activity they are fully spread out, and act as 'paddles,' by aid of which the animal is enabled to glide through its native element with a graceful serpentine motion. ”

“ None, however, have more than six gill-arches; they have no scales on the head, muzzle, or jaws; the dorsal spines, when depressed, fall into a longitudinal groove on the back; and the air-bladder is always divided into two distinct sacs, connected by a narrow neck. These too are chiefly inhabitants of warm latitudes, some marine, and some fluviatile; they do not possess much attractiveness of appearance, their colour being, in general, silvery grey, marked with dusky longitudinal lines. ”

“ The animal when extracted is an inch in length, of which the gill-tufts form one-third.
Mingled with these there are one or two specimens of a much more imposing species, the Hook-plumed Sabella. [147] It grows to a large size, the crown of gill-filaments sometimes attaining a height of an inch, and the same diameter. The two rows are incurved in regular spirals of half a turn, each consisting of about eighteen filaments, which are rather stout, the whole crown sometimes taking the form of a funnel, sometimes that of a cup, often arching inward at the tip. ”

“ Among the orders first defined by Gill are the Eventognathi, Nematognathi, Pediculati, Iniomi, Heteromi, Haplomi, Xenomi, and the group called Teleocephali, originally framed to include all the bony fishes except those which showed peculiar eccentricities or modifications. Dr. Gill's greatest excellence has been shown as a scientific critic. Incisive, candid, and friendly, there is [Pg 406] scarcely an investigator in biology, in America, who is not directly indebted to him for critical aid of the highest importance. ”

“ As thus arranged, the gills are really not active workers after their first draw during the remainder of their traverse, but simply carriers of the wool to the next set. It is somewhat remarkable, as may indeed be said of every invention, that this fact has only been just observed, and suggested an improvement. There is no reason why each gill should not be continuously working to the end of the traverse, and only cease during its return to its first position. ”

“ In the young plants of this genus the gills vary very much in color. They are whitish, clay-color, violet, dark purple, blood-red, etc., according to species, but, as the plants mature, the gills become dusted with the rust-colored falling spores, and with age usually become a rusty ochraceous, or cinnamon color. The stem in some of the species is distinctly bulbous and in others equal, cylindrical, or tapering. In identifying the species it is necessary, in order to ascertain the true color of the gills, to examine the plants at different periods of growth. ”

“ Thus, for example, the Amphibian larva, e.g. the tadpole of a frog (p. 153) has gills, which disappear in the adult form: the young reptile, bird, or mammal, which has no larval stage, has gills during a comparatively early stage; and loses them at a later period of its development. In each case zoologists conclude that the animal is descended from a fish-like ancestor, which possessed gills all its life, and that the more immediate ancestors in the family tree, have lost their gills by degrees. ”

“ If the water is not sufficiently well aerated, they rise to the surface, emit a bubble of air, and take a new supply into their lungs. As a rule they remain motionless under water, but the gills contract spasmodically and become paler, whereupon they fill again with blood and darken; the contrast between the pure white body and the carmine-red feathery gills is very beautiful. ”

“ This genus is so called from the mottled appearance of the gills. The pileus is somewhat fleshy, margin even, but never striate. The margin always extends beyond the gills and the gills are not uniform in color. The mottled appearance of the gills is due to the falling of the black spores. The gills do not deliquesce.
The stem is smooth, sometimes scaly, at times quite long, hollow. The veil, when present, is interwoven. ”

“ But it would be altogether too rash to predict that, because no such evidence will, in all probability, be afforded by Europe or America, the evidence of the intermediate link will never be furnished. Let it be remembered that the present home of the anthropoid apes is almost entirely unknown in a paleontological point of view. When Africa or Asia shall have been half as well explored as Europe, or even America, it may then be time to predict that such evidence will never be forthcoming. ”

“ With the evidences of the existence of man specialized as much as he is now, at a period so early as he is known to have lived, it is scarcely too rash to assert that it is useless to expect to find any evidence of his simian origin in any bones exhumed in the later formations in Europe, and much less in America. And, in view of the negative results of the extensive paleontological explorations made in Europe, it is almost as unlikely that any such remains will ever be found, even in the anterior formations. ”

“ The proportions of the fore limb to the hind, and of the median and distal portions of each to the proximal, so far from proving a condition intermediate between man and the apes, or embryonic or juvenile humanity, or even affinity to the negro, indicate that he was more unlike the apes in such respects than are some of the existing races; nor is this evidence rebutted by any characteristics of the skull, the dentition or otherwise, so far as the testimony allows us to judge. ”

“ The convex part of its bowl was below, and the great head, as an inverted toadstool, stood upright on a short, stem-like pedestal. The gills within were of a deep green color, and curved out from the center in the form of a spiral. This form, however, was not the distinguishing feature, for I had before observed specimens that were spiral in structure. The extraordinary peculiarity was that the gills were covered with fruit. This fruit was likewise green in color, each spore, or berry, being from two to three inches in diameter, and honeycombed on the surface, corrugated most beautifully. ”

“ The "Agarics," as already described on page 79, are distinguished by the feature of the gills, or thin laminated curtains—the hymenium—upon which the spores are produced, and from which they are shed beneath the mushroom. These gills vary in thickness and number in the various species, and in one genus are so short, thick, swollen, and branched as to give rather the effect of turgid veins than gills, as shown in the accompanying sectional drawing. We occasionally come upon one of these mushrooms in our walks, usually in the woods. ”

“ The under side of the cap is laid in plaits, called gills, from their resemblance to fish gills. They never grow fast to, or down upon, the stem, usually stopping short off, about one-tenth of an inch from its juncture with the cap. Mushrooms are cultivated in gardens or cellars. They grow from spores or little finger-like lengths, called spawn, which are produced by the spores. Mushrooms turn black or purplish after the first twenty hours of growth. When the gills have taken this dark hue, the mushroom is unfit to eat.
Some fungi grow in very wet places ”

“ The Gills.—Those vertical plates on the under surface of the mushroom, which radiate from the centre to the circumference, like the spokes of a wheel, are called Gills (lamellæ) ; they are not formed, as some have supposed, of layers of the reduplicated seed-membrane alone, but by a prolongation of the fibres of the pileus, which these merely invest. The fibrous structure is most apparent in Agarics with thick gills; in those where the flesh changes colour when bruised; or where, the interposed flesh remaining white, the hymenium is tinged with the colour of the ripening spores. ”