Balfour is the name of Jekyll's test subject in Bedlam; this is also the (largely unmentioned) name of his author: Robert Lewis Balfour Stevenson.
Squids actually do get almost as large as depicted in 20,000 Leagues Under the Sea. The Giant Squid can grow to be over 40 feet long. And the recently discovered Colossal squid can grow to be over 45 feet long and has almost twice the mass of the giant squid. However neither of these species had yet been officially documented in 1892.