SALIVA. 209 



changed. Other substances, treated in this way, are colored green 

 (as vaginal mucus), or are not changed in color. 



Origin and Uses. The spermatozoids are developed within the 

 spermatophori, as already stated, and are the part of the semen 

 indispensable to impregnation. The spermatophori are probably 

 developed from the spermatine, as cytoid corpuscles are in plasma, 

 as described on page 146. Their relation to the seminiferous tubes 

 of the testis will be explained in the chapter on "The Sexual 

 Organs." 



III. GLANDULAR SECRETIONS DISCHARGED INTO THE ALIMENTARY 



CANAL. 





 1. Saliva. 



Saliva, as obtained from the oral cavity, is a mixture of the 



icretions from the three salivary glands with the mucus of the 

 mouth. It is a cloudy, viscid, slightly opalescent fluid, without 

 taste or smell, and of alkaline reaction. Its specific gravity varies 

 from 1004 to 1006, and its solid constituents from 0.35 to 1 per cent. 



The only histological elements in saliva are epithelial cells and 

 cytoid (mucus) corpuscles; neither of which are, of course, peculiar 

 to it. 



The pure saliva varies with the gland secreting it, whether the 

 parotid, submaxillary, or sublingual. 



The secretion of the parotid gland has a specific gravity of 1006 

 to 1008.8, is clear as water, and without color, taste, or odor; and 

 contains 1.4 to 1.6 per cent, of solid constituents. It contains much 

 chloride of sodium and of potassium., 



The secretion of the submaxillary gland resembles the preceding, 

 but is more viscid, less strongly alkaline, and has a less specific 

 gravity (1004) and less solid residue (0.855 per cent.) ; and that of 

 the sublingual gland is the most viscid of the three. All of these 

 secretions contain a peculiar organic substance salivine, or ptyaline 

 (p. 83). 



Recent experiments give 3 pounds and 6J ounces (avoirdupois) 

 as the average quantity of saliva secreted by adults in twenty -four 

 hours. (Lehmann.) The quantity is increased by the mastication of 

 dry and hard alimentary substances, and by movements of the jaw, 

 whether in chewing, speaking, or singing. Acid, aromatic, and 

 pungent substances have the same effect. 

 14 



