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and more refined methods had to be adopted, which was only possible 
where the resources of a biological station such as that at La Jolla are 
available. A specially devised net of the finest bolting silk is towed for 
a very short time at a depth of 80 metres ; the catch is then transferred 
to a relatively large volume of water and hurried ashore in a fast motor 
boat (30 miles an hour), and at once distributed to the microscopes of 
the observer and his assistants. By this intensive study of living 
material carried out over a number of years, many very interesting 
results have been obtained quite apart from the records of new species ; 
results which are of great interest to the biologist. Many of these 
organisms are very brilliantly coloured, and also show a specialization in 
structure surprising even in the greatly diversified protozoa. 
Of the remarkable “ organelles ” described by Professor Kofoid as 
occurring in the dinoflagellates, there are two which are distinctly 
metazoan in character. In the “ ocellus ” of the Pouchetiidse we have 
a structure peculiar to this group alone amongst the protozoa, and in 
the genus Erythropsis, where it attains its highest development, there is 
a “ compact melanosome enclosing a red sensory core at the base of a 
concentrically laminated spherical lens.” 
Nematocysts, however, are not restricted to this group of the 
protozoa, being found throughout the Cnidosporidia and in at least one 
species of the Ciliata — Frontonia leucas. Their origin and presence are 
described in th§ genera Polykrikos and Nematodinium, where the 
author states that they are “ not less specialized than those found in 
the Ccelenterates.” 
The authors remove the genus Noctiluca from the group Cysto- 
flagellata, first defined by Haeckel, and definitely allocate it to the 
dinoflagellates, placing it in the G-ymnodinioidse. Pyrocystis is now 
recognized as an encysted or intermediate stage in the development of 
the Dinoflagellata ; the form Pyrocystis noctiluca first described by 
Murray being but the intermediate stage of Gymnodinium lunula 
Schiitt, an almost cosmopolitan species and found in all seas. One of 
the many interesting biological questions discussed in the introductory 
part of the monograph concerns the fundamental function of nutrition. 
In this group of organisms it has not reached that degree of differentia- 
tion which enables us to delimit the animal from the plant by this 
means — holozoic and holophytic nutrition may occur in different species 
in the same genus. Hence botanists and zoologists will alike continue 
to regard them as within their several fields of study. 
We heartily congratulate the authors on the completion of a very 
valuable contribution to biological science, one that will prove indis- 
pensable to the worker, whether he be engaged in “ plankton ” research 
or in oceanography. 
To draw particular attention to the few errors that mr.y be detected, 
mostly proof-reading errors, etc., would be ungracious, but attention 
should be drawn to one defect which raises a question ot some import- 
ance, in view of the permanent value of these records — the paper on 
which the monograph is printed can hardly be described as of a lasting 
quality. A. W. Sheppard. 
