A text book of physiology . an raw. The boiling destroys the pepsin clinging to thefibrin. 2 Briicke, Moleschotts Untersuch., VI. 474. 3 Cf. Mafy, Liebigs Annalen, Bd. 173 (1874), p. 227. 4 fjwiecicki, Pfliigers Archiv, xiii. (1876) p. 444. Partsch, Archiv f. micros. Anat.,xiv. (1877) 17J. Chap, i.] DIGESTION. 257 In the case of the salivary glands the phenomena to a certainextent differ according as the gland is a mucous gland, onecontaining a larger or smaller number of mucus-producing cells,and secreting a more or less viscid mucous saliva, or a serous gland,i. e. one containing no suc
A text book of physiology . an raw. The boiling destroys the pepsin clinging to thefibrin. 2 Briicke, Moleschotts Untersuch., VI. 474. 3 Cf. Mafy, Liebigs Annalen, Bd. 173 (1874), p. 227. 4 fjwiecicki, Pfliigers Archiv, xiii. (1876) p. 444. Partsch, Archiv f. micros. Anat.,xiv. (1877) 17J. Chap, i.] DIGESTION. 257 In the case of the salivary glands the phenomena to a certainextent differ according as the gland is a mucous gland, onecontaining a larger or smaller number of mucus-producing cells,and secreting a more or less viscid mucous saliva, or a serous gland,i. e. one containing no such mucus-producing cells, and secretinga thin limpid saliva free from mucus. The submaxillary glandof the clog may be taken as the type of mucous glands. If asection is prepared of this gland when at rest, i. e. when it hasnot for some time been actively secreting, the cells of the alveoli(Fig. 44) are found not to stain readily with carmine; and this lackof staining appears to be due to the fact that the greater part of the. Fig. 44. Section of a mucous gland, A in a state of rest, B after it lias been forsome time actively secreting. (After Lavdowsky.) a demilune cells, c leucocytes lying in the inter-alveolar spaces. The darkershading in both figures is intended to indicate the amount of staining. protoplasm of the cells has become converted into a mucin-bearingsubstance, only a small portion of unchanged protoplasm, easilystaining with carmine, remaining round the nucleus. In additionto these muciparous cells are seen a number of smaller half-moon-shaped (demilune) cells, the protoplasm of which stains deeply withcarmine. These half-moon cells, which lie outside the muciparouscells, between them and the basement membrane, are apparentlyyoung cells, frequently possess two or more nuclei, and in generalseem to be in a state of active growth and multiplication. When similar sections are prepared from a gland which has beenthrown into long-continued activity by stimulation of th
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