Researches into the comparative structure of the liver / by Joseph Leidy.

  • Leidy, Joseph, 1823-1891.
Date:
[1848?]
Catalogue details

Licence: Public Domain Mark

Credit: Researches into the comparative structure of the liver / by Joseph Leidy. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    In the lowest forms of vertebrated animal life, where no distinct digestive apparatus exists, we find no trace of biliary structure. When we rise a Utile in the scale, and arrive at animals with an internal digestive cavity, as the Polypi, it is probable that certain of the cells form ins; part of the parities of the cavity, may possess the power of secreting a fluid analogous to bile. Certain cellules, also, of the PolygCUtriea may be deTOted to this purpose. The few short area of the digestive cavity of many Med time may also be biliary in their nature. In the T.xnoidea and Trernatoda, animals which have a ramiform dig ive apparatus, the enseal appendages have been considered as a rudimentary form of the organ. They, however, do not differ in structure, which is granular, from the main portion of the cavity, and, like the latter, receive part of the alimentary matter. The cereal appendages of the digestive cavity of the Erhuiodernuila are reported as representing the biliary struc- ture, a question, as in several of the former instances, which I have not yet examined. In many Annelida there are cu-ca appended to the si ' the alimentary canal, which are lined by organic cells of small >:/.-, and probably secrete a biliary fluid, as in ffirudo, Arenieoht, ^r. In the Myriapoda, emptying into the intestine, there are several long and delicate tubes of basement membrane lined by secretin- cellules in the JuUdm averaging-0125 millimetre in diameter, which are no doubt of this nature; but as they do not differ in structure from corresponding tubes of insect*, a more particular description of the latter will answer for the former. Jnserts —In insects the liver consists of a number of distinct, Sfhite, ye- lowor brown, filiform, tortuous lubes placed in close apposition with the sides of the alimentary canal and opening into it, generally by separate orifices, frequently after joining each other to form short trunks, as in M*,ca, Tabanw, fcc., in the ricinity of the pyloric extremity of the stomach. The smallest number, which is lour, occurs in the fl.es (thptera); in the LtpidtpttT* there are six ; and in the Orthoptera and ffymenoptera they are numerous. When few in number, they are very long, sometime. three or four times the length of the intestinal canal; when numerous, they are proportionate!v short, and more delicate. In some ineectS they ternn- Ze in blind extremities as in many Diptora, in others they unue in p., s ^their farthest extremity, so« to form loops,as fa.the b-£(*V When -ore intimat^ examined, these tubes Plate I. Pig.. 2. «, 4, R, «Z fll to consist of a delicate tube of clear, transparent, amorphous I, membrane, the inner surface of winch IS covered with secretmg • From the thinness of the tube, the cdls often project so as t eelh. ' . . . ,,,,1,,,,] ,..,, »< n the flesh i, -, .rr.miUcJ appearance when viewed by ine n.,U u . >• . * H , „,™ W,.l (PL L Fig. Id -< I—* —'* **Z2 <• -i *—sTtfTTf :**-£-.«*«-* The secreting celLs [J L I. figs, i, , ;