ID this pre-1970 anatomy textbook for 9-year-olds?

While watching "The Wonder Years," during the 1990 "Tree House"
episode about "the talk," which never really took place, IIRC, Kevin
is reading an anatomy textbook from school. I'm pretty sure I
recognized the cover as that of a 1950s(?) textbook. Trouble is, I've
now forgotten the name - maybe it was "The Human Body"? I have a hunch
it was either the one by Cyril Bibby & Ian T. Morison OR the one by
Charles Herbert Best. Except that the latter was written in the 1930s,
and even though it's been updated since then, I have my doubts.

The one I remember had chapters about the circulatory system, the
nervous system, the muscular system, the skeletal system, the
respiratory system, the urinary system, the digestive system, and the
reproductive system. There were colored illustrations on just about
every page. One page I remember said that if you put your hands on
your hips with your thumbs in back, they will be pointing to the lower
ends of your kidneys. Another described fever as being like water in a
paper cup with a hole in it - that is, the water/heat is coming in
faster than it can get out, and in the case of fever, that's so as to
destroy the disease. (Sometimes?)

At any rate, I think the cover had a dark blue-violet background - and
I can't find anything in Google Images that seems to match - at least
not with those authors. Or in abebooks.com. Any ideas? Thanks.

Lenona.