50 Anatomy, Physiology, and Pathology of the 
often with great benefit. Occasionally, however, but very little 
gaseous matter escapes through the opening, a circumstance that 
depends upon the non-separation of the gas in a large and dis- 
tinct volume from the fermenting ingesta. Notwithstanding but 
very little gas may be liberated, still an advantage is gained by 
the operation ; for the sheath of the instrument employed in 
making the puncture forms a ready and convenient passage 
