168 AN AMERICAN TEXT-BOOK OF PHYSIOLOGY. 



describes his results as follows : When the animal is in a fasting condition the 

 cells have a granular appearance throughout their substance, the outlines of 



FlG . 71. Parotid of the rabbit, after stimulation of the sympathetic (after Heidenhain). 



the different cells being faintly marked by light lines (Fig. 72, A). When 

 the gland is made to secrete by giving the animal food, by injecting pilocarpin, 

 or by stimulating the sympathetic nerves, the granules begin to disappear from 



c D 



FIG. 72. Parotid gland of the rabbit in a fresh state, showing portions of the secreting tubules : A, in 

 a resting condition ; B, after secretion caused by pilocarpin ; C, after stronger secretion, pilocarpin and 

 stimulation of sympathetic ; D, after long-continued stimulation of sympathetic (after Langley). 



the outer borders of the cells (Fig. 72, _B), so that each cell now shows an outer 

 clear border and an inner granular one. If the stimulation is continued the 

 granules become fewer in number and are collected near the lumen and the mar- 



