Old Mac can't read new macbook formatted external drive?

HELP!
I just got hit with a double whammy. :Imac running Panther did something odd to the it's external drive. That was formatted fat 32.
I plan to see if anyone in the nearby computer repair class can recover those files, but in the meantime (days!) the gremlin also hit the macbook, putting it in range of a spill.

So now the only backups I have are on the second external drive formatted with a mac format on the macbook. This one was done with 2 partitions, one for Time Machine, one for the stuff I was yanking over from the other hard drive.

So now I find that Imac can't even SEE the second drive. (Not that I expected it to see or recognize Time Machine, just the other part.)
My macbook is on downtime until it gets checkup/cleaning (with all mac places nearby apparently closed thru New Years and classes I need it for starting right after)

Does anyone know a way to get "Ye Old Imac" to see the other drive? Is there a driver or something? I know it's very hard to find older software (most online sites don't go back past Tiger), but it is a mac format for goodness sake!
I can't even be 100% sure if it's something to do with a newer mac format for the external drive or "Ye Old Imac" is just being grumpy. It seems to see the other USB stuff but it has been known to lose touch with them.

And, of course, the web class I use it for only supplies PCs, which certainly can't read it either.