File:Text-book of comparative anatomy (1898) (14592352800).jpg

Identifier: textbookofcompar01lang (find matches)
Title: Text-book of comparative anatomy
Year: 1898 (1890s)
Authors: Lang, Arnold, 1855-1914 Bernard, Henry Meyners Bernard, Matilda Haeckel, Ernst Heinrich Philipp August, 1834-1919
Subjects: Anatomy, Comparative
Publisher: London, New York, Macmillan and Co.
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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s of appendages, which we may also consider as modified Medusa : A. The gonophores or reproductive persons (Fig. 83, gov go.2, go3).-To these belong exclusively the function of forming the sexual products. They are either male or female. The typical organisationof a Craspedote Medusa is still more or less faithfully maintained inthem. They possess a bell-shaped umbrella with velum, circumferen-tial canal and radial canals, and, further, a gastric peduncle whichprojects into the subumbrellar cavity (occasionally with an oralaperture in addition), and in whose wall, as in the Codonidce among the> raspedote Medusce, the sexual products arise. The umbrella is here,probably, a protective apparatus. Occasionally the rudiments oftentacles are still found on the margin of the disc. Sometimes, how-ever, the Avhole M-dusa form is considerably degenerated. B. Sterile persons.—These perform the functions of taking in food,and digestion, of protection, touch, etc. The Medusa structure in them
Text Appearing After Image:
FIG. So.—Praya galea, after Haeckel. 112 COMPARATIVE ANATOMY CHAP. is always obscured, and often so much so as to be unrecognisable.The following different kinds of such sterile persons may be dis-tinguished : a. Persons in which the following typical organs of a Medusa maystill be recognised: (1) a variously-shaped protective or bract asmetamorphosed umbrella. It serves as umbrella or shield, and affordsprotection, not only to the other parts of the same person, but alsoto the neighbouring persons, which can withdraw under it. (2) Theoral or gastric peduncle (siphon), the chief organ for taking in foodand digestion. The siphon is often stalked, and the edge of themouth widened into a funnel, or produced into 4 points, or prolongedlike a proboscis. (3) A very contractile tentacle or capturing filament,which is placed at the base of the gastric tube. The tentacle isfeathered on one side, i.e. it is provided with one row of lateralbranches, whose ends are armed with stinging batteries

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