Pugging

My church in Newton, MA is looking at HVAC upgrades, and had someone look at the state of insulation in the walls. Looking in two places, a carpenter found that there was a layer of plaster/lath in the middle of each bay. I found a description of another house with this sort of invisible wall, which one writer called "pugging" claiming it was a German building tradition. Pugging, according to a book from 1883, is rather putting plaster and horsehair between floors to dampen sound: http://books.google.com/books?id=wns6AAAAMAAJ&pg=PA50&lpg=PA50&dq=pugging+plaster&source=bl&ots=wdWbqa8dlV&sig=hoZLr-Fz_HOgw-omQlVlkQNASNA&hl=en&sa=X&ei=mmUYT5aOBebh0QGz6Y2XCw&ved=0CCIQ6AEwAA#v=onepage&q=pugging%20plaster&f=false