ABSTRACT
The evolution of the human body resembles that of the British constitution. It is full of relics of the past, as curious as the judges' wigs or the city companies, but for most of these vestiges a new function has been evolved. If people observe single cells, such as the protozoa, bacteria, or the diatoms and other microscopic plants in sea water which are the ultimate source of almost all the nourishment of sea beasts, people find that they are often remarkably hard to keep alive. The blood plasma of many marine animals is almost the same as sea water, with the addition of a little sugar and other foodstuffs on the way from the gut to the cells, and waste products on the way from the cells to the excretory organs. Most marine animals, both vertebrate and invertebrate, shed their eggs and spermatozoa into the sea, and rely for fertilization on the numbers and swimming power of the latter.
