A Practical Physiology

with 13 of the 70 elements, namely: oxygen, hydrogen, nitrogen, chlorine, fluorine, carbon, phosphorus, sulphur, calcium, potassium, sodium, magnesium, and iron. Besides these, a few of the other elements, as silicon, have been found; but they exist in extremely minute quantities.

The following table gives the proportion in which these various elements are present:

Oxygen

62.430

per cent

Carbon

21.150

" "

Hydrogen

9.865

" "

Nitrogen

deals with the form and structure of the human body, and describes how the different parts and organs are arranged, as revealed by observation, by dissection, and by the microscope.

Histology is that part of anatomy which treats of the minute structure of any part of the body, as shown by the microscope.

ses.

The word anatomy, however, is usually employed instead of morphology. It is derived from two Greek words, and means the science of dissection. Human anatomy the