. The biology of the frog. Frogs. A' R Fig. 6o. — Diagram show- ing the position of the thyroid glands, t; I, lateral process of hyoid cartilage; /./, thyro- hyoid process of hyoid. tion in Rana pipiens. convert the proteid-splitting enzyme of that organ into an active form. Doubt has, however, been recently thrown upon this conclusion. The Thyroid Glands. —The thy- roid glands of the' frog are com- pletely separated from each other, being situated on either side of the hyoid apparatus in a small space between its posterior lateral and thyro-hyoid processes. Gaupp has described some thyroid ti
. The biology of the frog. Frogs. A' R Fig. 6o. — Diagram show- ing the position of the thyroid glands, t; I, lateral process of hyoid cartilage; /./, thyro- hyoid process of hyoid. tion in Rana pipiens. convert the proteid-splitting enzyme of that organ into an active form. Doubt has, however, been recently thrown upon this conclusion. The Thyroid Glands. —The thy- roid glands of the' frog are com- pletely separated from each other, being situated on either side of the hyoid apparatus in a small space between its posterior lateral and thyro-hyoid processes. Gaupp has described some thyroid tissue (ac- cessory thyroid) on the ventral side of the hyoglossus muscle, and I have been able to confirm this observa- The tissue of the thyroid shows a unique structure, being composed of a mass of rounded follicles united by a small amount of con- nective tissue in which there is a rich supply of blood ves- sels. Each follicle is a perfectly closed sac Hned by a sin- gle layer of cubical epithelial cells. In the center of each follicle is a colloidal mass of transparent substance which probably represents the secretion of the epithelial lining. The thyroid of the frog, Hke that of the higher vertebrates, has been found to secrete a substance rich in iodin (iodo-. e-" Fig, 6i. — Part of a cross section of the thy- roid of Rana pipiens. e, epithelial layer of vesicles; m, colloidal substance in Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Holmes, Samuel J. (Samuel Jackson), 1868-1964. New York, The Macmillan company;[etc. ,etc. ]
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectfrogs, bookyear1906
