Cheap (household) alternative to proto-slow??

[hcorbett at garnet.berkeley.edu]

Methylcellulose (also seen as Methyl Cellulose) in solution is a non-toxic
way to slow down protists and bacteria under the coverslip. I don't know 
where you could get it ordinarily, but it's available from Carolina
Biological Supply - some huge quantity for $20 or so. It sounds similar to
this "proto-slow"/

Heather