436 THE ZOOLOGIST. 
NOTICES OF NEW. BOOKS. 

Conditions of Life in the Sea; a Short Account of Quantitative 
Marine Biological Research. By James JoHNstonrE. Cam- 
bridge: At the University Press. 
‘Te sea and its animal life is a fascinating subject for 
naturalists ; for the evolutionist it qualifies and enlarges his 
purview if he has hitherto based his conclusions alone on 
terrestrial biology, while to all thinkers the conditions of life in 
oceanic depths is a problem they would fain solve. Mr. John- 
stone’s volume fully sustains the standard value in the Cambridge 
Biological Series, and is a welcome addition to the subjects 
already treated in those excellent books. 
Oceanographical discovery may now be said to start from the 
‘ Challenger’ Expedition of 1872. Much was done before that 
notable voyage, and much more has been accomplished since, 
but it focussed what was then known, and so immeasurably 
added to our knowledge that the ‘Challenger’ will always be a 
household word among marine biologists, and its discoveries are 
frequently referred to in the pages of this book. Haeckel, in his 
‘ Piankton-Studien,’ gave to the terms ‘‘ Plankton,” ‘‘ Benthos,”’ 
and ‘‘ Nekton”’ an illuminative value which nothing can dim, 
though, as Mr. Johnstone writes, there is of course no absolute 
distinction between these three classes of organisms; “‘but this 
lack of absolute distinction, which is to be felt in all schemes of 
classification of natural objects, is no argument against the use 
of a series of terms which are sufficiently exact, are expressive, 
and have great practical convenience.” These remarks may 
well be pondered by some advocates of a dogmatic taxonomy. 
The struggle for existence in the sea is no less severe, if not 
even more so, than on land. ‘‘ Countless millions of Pteropods 
must be destroyed by the Whales of the northern seas ; Porpoises 
destroy hosts of Herring, Cod, Whiting, and other fishes; roving 
Sharks and Dogfishes, either singly or in shoals, must at times 
