Hazel,
Venini (Scarpa and Martinuzzi) made a lot of pulegoso as did Seguso. i can't always tell the difference but seems that the color(s) used, pontil vs. polished base and the density of the bubbles are all clues - unless you've got a signature, acid etched or otherwise

i'd guess that it was produced by one of these two glass houses, though i wouldn't venture a guess as to the artist.
i suppose that there were other makers that could have made it as well but i don't know much else. maybe someone with more knowledge will come along and help us both learn a bit more
bidda