with a single specimen, as, for example, Johannes Muller did half a
century ago with the one available specimen of amphioxus, the lowest of
vertebrates, then recently discovered. What Muller learned from that one
specimen seems almost miraculous. But what if he had had a bucketful of
the little boneless creatures at his disposal, as the worker at Naples
now may have any day for the asking?

When it comes to problems of development, of heredity, a profusion
of material is almost a necessity. But here the creatures of the sea
respond to the call with amazing proficiency. Most of them are, of
course, oviparous, and it is quite the rule for them to deposit their
eggs by hundreds of thousands, by millions even. Everybody knows, since
Darwin taught us, that the average number of offspring of any given
species of animal or plant bears an inverse proportion to the liability
of that species to juvenile fatalities. When, therefore, we find a fish
or a lobster or other pelagic creature depositing innumerable eggs, we
may feel perfectly sure that the vast majority of the eggs themselves,
or the callow creatures that come out of them, will furnish food for
their neighbors at an early day. It is an unkind world into which
the resident of the deep is born. But his adversity is his human
contemporary's gain, and the biologist will hardly be blamed, even by
the most tender-hearted anti-vivisectionist, for availing himself freely
of material which otherwise would probably serve no better purpose than
to appease the appetite of some rapacious fish.

Their abundance is not the only merit, however, of the eggs of pelagic
creatures, in the eyes of the biologist. By equal good-fortune it
chances that colorless things are at a premium in the sea, since to
escape the eye of your enemy is a prime consideration. So the eggs in
question are usually transparent, and thus, shielded from the vision
of marine enemies, are beautifully adapted for the observation of the
biologist. As a final merit, they are mostly of convenient size for
manipulation under the microscope. For many reasons, then, the marine
egg offers incomparable advantages to the student of cell life, an egg
being the typical cell. And since nowadays the cell is the very focus of
attention in the biological world, the importance of marine laboratories
has been enhanced proportionately.

But of course not all the work can be done with eggs or with living
specimens of any kind. It is e