Here you go - a really useful site.

http://theseedsite.co.uk/seedlings.html

Notable because it has many pics of seedlings (including, I think, campanula glomerata) and tons of useful germination info - most especially, because the seeds are always grown in the most basic conditions (as I do) with no faffing around with special treatments or hormones etc.

Thanks! I appreciate you taking your time to answer my question and share that link!