306 



PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



and seem to be cells in a state of active growth and multiplication. 

 When a similar section is prepared from a salivary gland which has been 

 exhausted by prolonged stimulation of the chorda tympani nerve, the 

 muciparous cells will, as a rule, have largely disappeared. All the cells 

 are now small in size and all stain deeply (Figs. 126, 127, and 128). It 

 would appear from this that in such a gland stimulation of the chorda 

 nerve leads to a discharge of mucin, or to a total breaking down of the 



FIG. 126. ORBITAL GLAND OF THE DOG IN THE RESTING CONDITION. (Heidenhain.) 



FIG. 127. ORBITAL GLAND OF DOG COMMENCE- 

 MENT OF CHANGES DURING ACTIVITY, AFTEK 

 LADVOVSKY. (Heidenhain.) 



FIG. 128. ORBITAL GLAND OF DOG- 

 HIGHEST DEGREE OF CHANGE IN 

 ACTIVITY, AFTER LADVOVSKY. 

 (Heidenhain. ) 



entire cell, whose place is then taken by the new, rapidly growing, half- 

 moon cells. Both statements are probably correct. 



It is thus seen that the secretion is the result of the activity of the 

 protoplasm of the secreting cell. During rest the mucous gland manu- 

 factures mucin at the expense of its protoplasm. When such a gland 

 secretes, the mucin is discharged and new protoplasmic cells are rapidly 



