The Foamy Cicadella 



It may possibly happen that the insect's 

 well supplies water that is not quite pure. 

 If left to evaporate in a watch-glass, the 

 clear drop that trickles from the mass of 

 foam yields a thin white residue, which dis- 

 solves by effervescence in nitric acid. This 

 residue might well be carbonate of potash. 

 I also suspect the presence of traces of 

 albumen. 



Obviously, the Cicadella finds something 

 to feed on at the bottom of the puncture. 

 Now what does she consume? To all ap- 

 pearances, something with an albuminous 

 basis, for the pigmy herself is, for the most 

 part, but a grain of similar matter. This 

 element is plentiful in all plants; and it is 

 probable that the insect uses it lavishly to 

 make up for the expenditure of gum needed 

 for the formation of froth. Some albu- 

 minous product, perfected in the digestive 

 canal and discharged by the intestine as and 

 when the blow-pocket expels its bubble of 

 air, might well give the liquid the power of 

 swelling into a foam that lasts for a long 

 time. 



If we ask ourselves what advantage the 

 Cicadella derives from her mass of froth, a 

 very excellent answer is at once suggested: 



443 



