Handmade History : Frog Spittle

This passage from an 1864 history of papermaking intrigues:

1800. Sometime during this or the previous year
P. De Labigarre, who resided at Upper Red Hook,
brought a bag of frog-spittle to the paper-mill at Cats-
kill, which was manufactured into a poor kind of
paper. Several persons became interested in the experiment, and it was supposed by them to be a great discovery.

Frog-spittle?

A little more research reveals that the substance in question is not in fact the saliva of frogs, but the threadlike algae that grow on ponds (and which often hold frog eggs).