Page:Popular Science Monthly Volume 34.djvu/111

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eminent physicians and scientific men generally in this country or in the world. I believe that such information would be of more value to the world, after having been properly digested, than all the facts about the manufacture of cotton cloth, the raising of tobacco, the production of whisky, etc., that could be collected in a century. For do we not all desire to live long?



IN addition to the organs of which I have attempted in the preceding chapters to give some idea, and to those which from their structure we may suppose to perform analogous functions, there are others of considerable importance and complexity, which are evidently organs of some sense, but the use and purpose of which are still unknown.

"It is almost impossible," says Gegenbaur,[2] "to say what is the physiological duty of a number of organs, which are clearly sensory, and are connected with the integument. These enlargements are generally formed by ciliated regions to which a nerve passes, and at which it often forms enlargements. It is doubtful what part of the surrounding medium acts on these organs, and we have to make a somewhat far-fetched analogy to be able to regard them as olfactory organs."

Among the structures of which the use is still quite uncertain are the muciferous canals of fishes. The skin of fishes, indeed, contains a whole series of organs of whose functions we know little. As regards the muciferous canal, Schultze has suggested[3] that it is a sense-organ adapted to receive vibrations of the water with wave-lengths too great to be perceived as ordinary sounds. Beard also leans to this same view. However this may be, it is remarkably developed in many deep-sea fish.

In some cases peculiar eye-like bodies are developed in connection (though not exclusively so) with the muciferous canal. Leuckart,[4] by whom they were discovered, at first considered them to be accessory eyes, but subsequent researches led him to modify this opinion, and to regard them as luminous organs.

  1. From "The Senses, Instincts, and Intelligence of Animals," by Sir John Lubbock. "International Scientific Series," vol. lxiv, in press by D. Appleton & Co.
  2. "Elements of Comparative Anatomy."
  3. "Ueber die Sinnesorgane der Seitenlinie bei Fischen und Amphibien," "Arch, für mic. Anat.," 1870.
  4. "Ueber muthmassliche Nebenaugen bei einem Fische." Bericht über die 39 Vers., "Deutscher Naturforscher," Giessen, 1864.