530 
ROSE LOUSE. 
proof of it. This gentleman took the insects as 
soon as they were brought forth, and kept each in- 
dividual separate. The females of these brought 
forth abundance of young, which he treated in the 
same manner with precisely the same effect : thus 
he proceeded to the ninth generation with the same 
success ; and was so far from believing them ex- 
hausted, that he thinks it might be carried on to 
the thirtieth generation. 
There is something very singular in the quality 
of the glutinous liquor voided by these insects. 
« Were a person,” says Mr. Curtis, “ accidentally 
to take up a book in which it was gravely asserted 
that in some countries there were certain animals 
which voided liquid sugar, he would soon lay it 
down, regarding it as a fabulous tale, calculated to 
impose on the credulity of the ignorant ; and yet 
such is literally the truth. The superior size of 
the aphis salicis will enable the most common ob- 
server to satisfy himself on this head. On looking 
steadfastly on a group of these insects while feeding 
on the bark of the willow, one perceives a few of 
them elevate their bodies, and a transparent sub- 
stance evidently drop from them, which is imme- 
diately followed by a similar motion and discharge 
like a small shower from a great number of others. 
At first I was not aware that the substance thus 
dropping from these animals at such stated intervals 
was their excrement, but was convinced of its being 
gQ afterwards 5 for on a more accuiate examination 
I found it proceeded from the extremity of the ab- 
