PLEA FOR SYSTEMATIC ATTENTION TO AQUATIC BIOLOGY. 143
one another, i.e. to their biological environment, and (3) the
relation to their physical environment.
The number of problems connected with the occurrence and
habits of individual species of aquatic organisms is extremely
great. Probably each separate species has some peculiarities
of habitat or activity which require special investigation, in
addition to those which it may have in common with a number
of other species. As yet only a very limited number of forms
have been observed at all closely from this point of view, so that
there remains here an almost unlimited field for further research.
Information is indeed still wanted about every species as to where
and when it occurs and what it eats (if it does eat) and what it
does. For instance, although a very great deal is known about
the higher aquatic vegetation, as is at once apparent from a glance
at Mrs. Arber's extremely valuable book on "Water Plants,"
these plants would well repay further study in the field, and a
careful perusal of Mrs. Arber's book will suggest many lines of
work. And when it comes to the lower aquatic vegetation, espe-
cially the algae there is very much more to be learned about them
than is already known. As with the plants, so it is with the
animals. Even with regard to those which have received the
greatest amount of attention, such as the fishes and molluscs,
further information about their local distribution and habits is
still required. I think I can also safely say that the habits of
many aquatic insects and insect larvae are far from being properly
worked out, although a thorough knowledge of some of these
may very likely prove as useful as the detailed knowledge of
gnat larvae has been in connection with the fight against malaria
and other diseases. But it is obviously impossible on this oc-
casion to go into detail on this particular part of the subject.
Suffice it to say that there undoubtedly remains a more virgin
field for further scientific observations on the habitats and habits
of aquatic than of terrestrial organisms, while there is for
the individual worker at least the same pleasure in the one
case as in the other in finding even well-known species in new
and unexpected situations, and the same fascination in watching
the living organisms and speculating upon the significance of
their varied activities.
Turning to the problems connected with the inter-relation-
ships or biological environment of aquatic organisms, the most