228 
Dr. Kidd on the 
similar organ is represented in Sir Everard Home's Compa- 
rative Anatomy, vol. i. pi. 84, as belonging to the Cape 
grasshopper ; it was originally considered by Mr. Hunter, 
and is considered generally at present, as answering to the 
livet of the higher classes of animals. 
Each of these tubes springs out of a common cavity in 
which the white tube from the intestine terminates ; but at 
their free extremity they are all impervious. Each tube 
appears partially filled with a granular pulpy substance which 
is almost universally of a bright yellow colour; though 
sometimes a particle is visible here and there of a clear light 
green colour, and I have seen similar green particles in the 
duct leading from the intestines. 
The following peculiarity is observable in the individual 
structure of these tubes : their diameter for about one-third 
of their course from the closed extremity is very small, and 
they are colourless, and apparently empty ; after which they 
suddenly undergo a considerable enlargement, become yel- 
low, and are partially filled with the contents above de- 
scribed. 
Maceration in water destroys the yellow colour in the 
course of a few minutes ; from whence it may be inferred, 
that after death the colouring matter transudes through the 
tubes containing it — a circumstance observable also with re- 
spect to the biliary vessels of the higher orders of animals ; 
but it seems certain that no such transudation takes place 
during the life of the animal ; for, upon examination of the 
insect soon after death, I have never found the adjacent parts 
coloured, as they would have been by the escape of the con- 
tents of the tubes. 
