34 HOUSE, GARDEN, AND FIELD 



know that it bleeds freely if wounded, so it must contain 

 blood-vessels, that is, veins and arteries. There is a 

 pulsating artery which can be felt through the skin of 

 the wrist ; do you know how to find it ? It not, you will 

 be told by and by. We can see a few of the surface-veins 

 through the thin skin of the back of the hand. Notice 

 that they are irregular in arrangement, differing in different 

 persons, and often differing in the two hands of the same 

 person. They branch frequently, and run into one 

 another, forming irregular circles or ovals. If you happen 

 to have in the back of your hand a pretty long vein with 

 very few connecting branches, you can show in which 

 direction the blood of a vein flows. Let your hand hang 

 down till the vein becomes gorged with blood. Then press 

 it hard with a finger-tip. The vein becomes empty just 

 above that point, while below it is as full as ever. The 

 same thing can be still better seen in the veins of the 

 arm. The observation that blood in a vein accumulates, 

 not on the heart-side of an obstacle, but on the side away 

 from the heart, had some little effect in convincing men 

 that the blood in a vein regularly flows towards the heart, 

 and not away from it, but there are much more convincing 

 proofs than this. 



The hand must contain innumerable nerves, for it is 

 sensitive in every part. The presence of nerves is also 

 shown by the fact that we can move separate fingers and 

 even separate joints at pleasure. There are not only 

 nerves which convey impressions to the brain or spinal 

 cord (nerves of sensation), but nerves which convey im- 

 pressions from the brain or spinal cord to the muscles, and 

 so originate movements (nerves of motion). 



Then we have in the hand a good deal of flesh, the 

 same kind of substance which when cooked and set before 

 us at table we call meat. Flesh or meat is stringy, being 

 composed of long fibres, which are attached, usually at 

 both ends, to the bones. When a fibre contracts or 

 shortens, it pulls the bones, and that bone which is most 



