STM, an Apple ][+ emulator for the Mac, is available at
<ftp://cassandra.ucr.edu/pub/apple2/STM/>.  Note that STM runs ONLY
in 256 colors and will not work on black and white Macs.

STM will NOT let you use your old Apple ][+ disks on your Macintosh (and
you'd have trouble cramming those old 5.25" disks into a 3.5" disk slot,
anyway).  The comp.emulators.apple2 FAQ, which is available at
<ftp://rtfm.mit.edu/pub/usenet/comp.emulators.apple2/>, lists several ways
to transfer disk images, most of which involve cables or modems.  There
are already lots of Apple II disk images available at
<ftp://minnie.cs.adfa.oz.au/pub/apple2/>.  You must use a program
like ResEdit to change each disk image's type to DSK5 and creator to A2EM
for them to work with STM.