STRTJCTrRE OF GLA1TDS. 



253 



animal kingdom ( 370) probably required the singular un- 

 folding of the glandular elements which we observe among its 





Fig. 254. The glands of insects which secrete the acrid or corroding 

 juice, after Leon Dufour, An. cf. Sc. Nat. T. vii. pi. 19 and 20. A, of 

 Chlaenius velutinus. B, of Brachinus crepitans. C, of Calathus fulvipes. 



the glandular system in man and the more perfect animals, no better 

 method could be followed than to pursue a single gland through the class 

 of insects. As supplementary to this part of our subject, the elegant 

 forms which the clustered canals and vesicles of others of the special 

 secreting organs of insects exhibit may be referred to in the subjoined 

 figures. 



