636 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
constantly bring the provision transports into the deep sea (15, pp. 49, 
57). Thither, in addition, come the immense quantities of marine plant 
and animal corpses, which daily sink into the depths and are borne 
away by currents. Thither comes the constant “rain” of the corpses 
of zonary Protozoa (especially Globigerina and Radiolaria), which 
uninterruptedly pour down through all the zones of depth into the 
deepest abysses, and whose shells form the most abundant sediment of 
the deep sea, the calcareous Giobigerina ooze and the siliceous Radiolaria 
ooze. In general, it seems to me that the daily supply of food materials 
which the decaying corpses of numberless mariné organisms furnish to 
the others, is much more important than is commonly supposed.* How 
much food would a single dead whale alone furnish? 
But especially important and not sufficiently valued in this regard, 
it seems to me, is the trophic importance of the benthos for the plankton. 
Immense quantities of littoral benthos are daily carried out into the 
ocean by the currents. Here they soon disappear, since they serve as 
food for the organisms of the plankton. If one weighs all these com- 
plicated reciprocal relations, he obtains without counting a sufficient 
general conception of the “cycle of the organic material in the marine 
world.” : 
COMPARATIVE AND EXACT METHODS. 
The farther the two great branches of biology, namely, morphology 
and physiology, have developed into higher planes during the last 
decade, so*much farther have the methods of investigation in both 
sciences diverged from one another. In morphology the high worth of 
comparative or declarant methods has always been justly more recog- 
nized, since the general phenomena of structure (e. g., in ontogeny and 
systemization) have been in great part removed from exact investi- 
gation, and comprise historical problems, the solution of which we can 
strive for only indirectly (by way of comparative anatomy and phylo- 
genetic speculation). In physiology, on the other hand, we constantly 
strive to employ the exact or mathematical methods, which have the 
advantage of relative accuracy and which enable us to trace back the 
general phenomena of vital activity directly to physical (particularly 
to chemical) processes. Plainly it must be the endeavor of all sciences 
(of morphology also) to find and retain as much as possible this exact 
mode of investigation. But it is to be regretted that among most 
branches of science (and particularly the biological ones) this is not 
possible, because the empirical foundations are much too incomplete and 
*Hensen values this source of food very slightly, because “‘ only a very few ani- 
mals live upon dead matter,” and explains it in this way, ‘‘ that material in a state 
of foul putrefaction requires a stronger digestive power than the organization of the 
lower animals can produce” (9, p.2). Imust contradict both ideas. The sponges live 
chiefly upon decaying organisms, as do also many Protozoa, Helminths, Crustacea, etc. 
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