THE SALIVARY GLANDS 



335 



In all the five systems there constantly occur three cellular layers : the intima, 

 epithelial, and propria. As regards their origin Schiemenz states that Systems I 

 and IV are new structures, that System III arises in part, and Systems II and 

 V wholly, from the silk-glands of the 

 larva. As the glands differ much in 

 the sexes, and in different species 

 and genera, Schiemenz believes that 

 their function is very manifold. 



In addition to those previously dis- 

 covered by Schiementz, Bordas has 

 detected two additional pairs of sali- 

 vary glands in the worker and male 

 honey-bee, i.e. the internal mandibular 

 and sublingual glands, so that in Apis 

 there are in all six pairs, and appar- 

 ently one unpaired. 



SALIVARY 



HEAD. 



BEAK 



&SOPHAOUS 



.SALIVARY GLAND 



SAL RESERVOIR. 



STOMACH .... 



'UODCtiUM 



MALFV6HIAN TUBES 



STOMACH. 



ILEUM. .1 



....MALPICHIAH TUBES 



..DUODtNJM 



L....3AECUM 



FIG. 327. Appendages of digestive canal of Belo- FIG. 828. Salivary and other glands of 



stoma After Locy. Banatra. After Locy. 



The delicate chitinous external layer of the gland is perforated 

 by many very fine pores through which the salivary fluid secreted 



