problem with nested $(call ...) inside $(eval $(call ...)

[gk]

I am having trouble understanding why the following macro 'rule2' is not 
evaluating the way I expect.
Is this a bug? In what order are nested $(call ...) statements evaluated?
Thanks for any insights.

# makefile
# this works
define hello1
echo hello $(1)
endef

# this doesn't work
define hello2
echo hello $(call word,$(1))
endef

define word
$(1)
endef

define rule1
rule1:
        @$$(call hello1,$(1))
endef

define rule2
rule2:
        @$$(call hello2,$(1))
endef

$(eval $(call rule1,world))

$(eval $(call rule2,world))
# eof

address@hidden junk]$ make rule1
hello world
address@hidden junk]$ make rule2
Makefile:22: *** Insufficient number of arguments (1) to function 
`word'.  Stop.

- Greg Keraunen