parenchyma

Previously blood and air had been thought to mingle freely in the fleshy parenchyma of the lungs, but the microscope now revealed the membranous alveoli at the ends of the tracheo-bronchial ramifications.

[I]n a Sponge, the Parenchyma, it seems, is but a kind of mucous gelly, which is very easily and cleerly wash'd away.