Chap, XXI. INSECTS WHICH DISTIL WATER. 281 



one of the smaller branches, and there keep up a constant 

 distillation of a clear fluid, which forms a little puddle on the 

 ground below. If a vessel is placed under them, it will 

 receive three or four pints of it in the course of a single night, 

 The natives say that if a drop falls into the eyes it ernes 

 inflammation. It is stated that the insects suck this fluid out 

 of the tree ; but I have never seen an orifice, and it is scarcely 

 possible that the tree can yield so much. Our own " frog- 

 hopper" (Aphrophora spumaria) or "cuckoo-spit," as it is called 

 when in the pupa state, from the mass of froth in which it 

 envelops itself, is an insect of similar powers, and, though 

 very much smaller, belongs I believe to the same family. 

 From observation I came to the conclusion that in each casd 

 the chief part of the moisture is derived from the atmosphere. 

 Finding a colony of these insects busily distilling on a branch 

 of the Micinus communis, or castor-oil plant, I denuded about 

 20 inches of the bark on the upper part of the branch, and 

 scraped away the inner bark, so as to destroy all the ascending 

 vessels. I also cut a hole into the heart of the branch, and 

 removed the pith and internal vessels. The distillation was 

 then going on at the rate of a drop in 67 seconds, or about 2 

 ounces 5^- drams in 24 hours. Next morning the distillation, 

 so far from being affected by the attempt to stop the supplies, 

 was increased to a drop every 5 seconds. I then cut the 

 branch so much that during the day it broke ; but they still 

 went on at the rate of a drop every 5 seconds, while another 

 colony on a branch of the same tree gave only a drop every 

 17 seconds. I finally cut off the branch ; but this was too 

 much for their patience, for they immediately decamped, as 

 insects will do from either a dead branch or a dead animal. 

 The presence of greater moisture in the air increased the 

 power of distillation, and the period of greatest activity was 

 in the morning, when the air and everything else was 

 charged with dew. Having but one day left for experiment, 

 I found that another colony on a branch, denuded in the same 

 way, yielded a drop every 2 seconds, while a colony on a 

 branch untouched yielded a drop every 11 seconds. I re- 

 gretted that I had no time to institute another experiment, 

 namely, to cut off a branch and place it in water, so as to keep 

 it in life, and then observe whether there was any diminution 



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