624 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
isms in single regions of currents, and has twisted it in favor of his 
theory of the regular distribution of the plankton: 
The tests of the volume of the plankton show that, five times in the north, once 
north of Ascension, extraordinarily larye catches (!) weremade. These must have been 
caused by various currents in this region, and can therefore be left out of consider- 
ation (9, p. 249). 
It seems to me that Hensen would have done better to take into 
consideration these and other facts observed by him relative to the 
unequal plankton distribution before he built up his fundamental, 
certainly adequate, theory of the equality of the same. This was to be 
expected, since he himself in his first oceanic plankton studies (1887) 
observed many ‘*‘remarkable inequalities,” and his own tables furnish 
proof of this. While he many times mentions the immense swarms of 
Meduse and declares this “quite superabundant accumulation to be 
mysterious,” he adds: ‘such places must be avoided in this fishery” (9, 
pp. 27, 65). When Hensen later, in comparing the different catches of 
copepods (one of the most important planktonic constituents), finds 
that the distribution of the plankton in the ocean is very irregular 
and that the constitution of this seems to very strongly contradict 
his general conceptions of natural life (9, p. 52), he holds it to be best 
that these catches, which are of “such a different kind, should be 
excluded from consideration” (pp. 51, 53). Also, in the case of Sagi tta, 
which Hensen reckons with the copepods as belonging to the uniform 
perennial plankton, he finds “throughout not the equality which one 
might expect, but much more remarkable variations” (p. 59). 
These “surprising inequalities,” ‘variations even to tenfold,” he finds 
in case of the Daphnide (pp. 54, 56) and Hyperida (p. 57), the pelagic 
larve of snails and mussels (pp. 57, 58), Appendicularia and Salpa 
(pp. 63, 64), the Medus@ and Ctenophores (64, 65), the Tintinnoids (p. 
68), the Peridinie (p. 71), and even in the Diatoms (p. 82)—in brief, 
in all groups of pelagic organisms which by the numerous production 
of individuals are of importance for the plankton and upon which 
Hensen employs his painstaking method of calculation by quantitative 
planktonic analysis. If one freely “sets apart from consideration” 
all these cases of remarkable inequality (because they do not fall in 
with the theoretically preconceived ideas of the equality of planktonic 
composition), then finally the latter must be proved by counting. 
Bathycurrents or deep streams.—Through recent investigations, par- 
ticularly of Englishmen (Carpenter, Wyville Thompson, John Murray, 
et al.), we have become acquainted with the great importance of the 
submarine currents or deep streams. It has been demonstrated that 
the epicurrents, or the surface streams, furnish us no evidence rela- 
tive to the understreams to be found below them, which we name bathy- 
currents. These undercurrents may in different depths of the ocean 
have a quite different constitution, direction, and force from the over- 
currents. This is as true of the great oceanic as of the local coast ceur- 
rents. Ifthe more accurate stady of marine currents is a very difficult 
