function show(image) {
var show = document.getElementById(image);
show.src = 'http://www.wellesley.edu/Activities/homepage/cg/Images/' + image + 'on.jpg'
}
function hide(image) {
var hide = document.getElementById(image);
hide.src = 'http://www.wellesley.edu/Activities/homepage/cg/Images/' + image + '.jpg'
}