APPABBJNT PRODUCTION OF WATEE. 29 



morning. . . To the question, Whence is tliis fluid derived 1 the 

 people reply that the insects suck it out of the tree, and our own 

 naturalists give the same answer. I have never seen an orifice, and 

 it is scarcely possible that the tree can yield so much. A similar, but 

 much smaller homopterist insect, of the family Uercopidce, is known 

 in England as the frog-hopper (Aphrophora spumaria) when full- 

 grown and furnished with wings ; but while yet in the pupa state it 

 is called ' Cuckoospil,' from the mass of froth in which it envelopes 

 itself. The circulation of sap in our climate, especially in the 

 Graminacese, is not quick enough to yield much moisture. The 

 A&ican species is five or six times the size of the English. In the 

 case of branches of the fig-tree, the point the insects congregate on 

 is soon marked by a number of incipient roots, such as are thown out 

 when a cutting is inserted in the ground for the purpose of starting 

 another tree. I believe that both the English and African insects 

 belong to the same family and differ only in size, and that the chief 

 part of the moisture is derived from the atmosphere. I leave it for 

 naturalists to explain how those little creatures distil, both by night 

 and day, as much water as they please, and are more independent 

 than Her Majesty's steam-ships, with their apparatus for condensing 

 steam, for without coal their abundant supplies of sea water are of no 

 avail. I tried the following experiment : — -Finding a colony of these 

 insects busily distilling on a branch of the Riciiius communis, or 

 castor-oil plant, I denuded about 20 inches of the bark, on the tree- 

 side of the insects, and scraped away the inner bark so as to destroy 

 all the ascending vessels. I also cut a hole in the side of the branch, 

 reaching to the middle, and then cut out the pith and internal 

 vessels. The distillation was then going on at the rate of one drop 

 each 67 seconds, or about 2 ounces 5 J drams in 24 hours. Next morning 

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

 supplies, supposing they had come up through the branch from the 

 tree, was increased to a drop every 5 seconds, or 12 drops per minute, 

 makiuf one pint (16 ounces) in evpry 24 hours. I then cut the 

 branch so much that during the day it broke ; but they stiU went on 

 at the rate of a drop every five seconds, while another colony on a 

 branch of the same tree gave a drop every 17 seconds only, or at the 

 rate of about 10 ounces 4|^ drams in 24 hours. 



" 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, which Indian hunters soon 

 know when they sit down on a recently killed bear. The presence 



