266 



PHYSIOLOGY OF THE INVERTEBRATA. 



The author* has also examined the Malpighian tubules of 

 Libellula depressa (Figs. 49 and 50), and has proved that they 

 have a renal function. 



Malpighian. -bibahs 



Fig. 49. — Malpighian Tubules of Libellula. 



Libellula depressa (the dragon-fly) is a voracious insect, which 

 lives in water, during its earlier stages, where it undergoes an 



imperfect metamorphosis, 

 the pupa finally creeping 

 out of the water, and chang- 

 ing into the imago. By ex- 

 perimenting with a large 

 number of the larval forms 

 of Libellula, the author has 

 extracted (from the larvse) 

 uric acid crystals, by using 

 similar methods to those 

 already described in this 

 chapter. 



In the imago or mature 

 form of the dragon-fly the 

 Malpighian tubules number from sixty to seventy, and are 

 branched. Under the microscope, a Malpighian tubule is 



*■ Proc. Boy. Soe. Edinh., vol; 15, p. 401. 



Fig. 55. — Malpighian Tubules of- 

 Libellula. 



A = Longitudinal section showing the va- 

 rious states of the epithelial lining. 

 B = Transverse section of tubule. X 230. 



