'There is also another pair running on each side through the
spinal marrow to the testicles, thin and delicate. There is,
further, a pair running a little underneath the cuticle through the
flesh to the kidneys, and these with men terminate at the testicle,
and with women at the womb. These veins are termed the spermatic
veins. The veins that leave the stomach are comparatively broad just
as they leave; but they become gradually thinner, until they change
over from right to left and from left to right.

'Blood is thickest when it is imbibed by the fleshy parts; when
it is transmitted to the organs above-mentioned, it becomes thin,
warm, and frothy.'