D.— ZOOLOGY 87 



which cannot be touched in any other way, while the marine stations and 

 fishery departments have the great advantage of continuous observation. 

 The only oceanic region in which continuous observation has been 

 attempted is the Antarctic where the ships of the Discovery Committee 

 have been working for the past thirteen years. Such work has proved 

 to be highly remunerative in results and similar regular long-term investi- 

 gations, designed to elucidate problems connected with the Gulf Stream, 

 are now beginning in the western North Atlantic. 



If I were asked to specify those branches of marine biology in which 

 we have recently made the greatest progress I should say physiology and 

 natural history. Very wonderful advances are being made in our under- 

 standing of function in marine animals, and this is due to the great volume 

 of important work achieved by those whom I may call the zoological 

 physiologists. Their researches are throwing a flood of light on many 

 difficult problems, and if I do not discuss their work in detail to-day it is 

 not that I do not recognise its significance and value, but rather that I feel 

 incompetent to do it adequate justice. 



In natural history we have made great strides. Work in this branch of 

 biology has, I believe, been stimulated by the fishery departments, for 

 when the importance and interest of the intensive study of individual 

 species of fish was recognised, zoologists became anxious to apply the 

 same methods to other marine animals. Though the need for correct 

 identification will always remain fundamental, the days when the zoologist 

 felt that his work was ended with a systematic diagnosis and the writing 

 of a label have long since passed, and in recent times most excellent work 

 has been done on the life-histories of marine animals and on their relations 

 to their organic and physical environment. In all groups of organisms 

 from diatoms to whales progress has been made, and for a goodly number 

 of species we can now answer the simple questions that spring to the lips 

 of every visitor to an aquarium : ' What does it eat ? ' ' How does it 

 breed ? ' ' How long does it live ? ' 



A most important feature of animal life in the sea is the constant 

 occurrence of large variations in abundance, and these, though they may 

 not be greater, appear to be more general in their incidence than in land 

 animals. We owe this knowledge mainly to the exact work carried out 

 by the fishery departments, but though it is of fish that we have the best 

 data there is no reasonable doubt that marine invertebrates are affected in 

 the same way. 



Annual fluctuations in the abundance of a fish may be very great. One 

 year may be exceptionally favourable, with production far above normal, 

 to be followed perhaps by several years of scarcity ; and it is not uncommon 

 to find that fish belonging to one year class are fifty times as numerous 

 as those of another. These great fluctuations, which are the foundation 

 on which fishery prediction is based, are for the most part to be attributed 

 to events which happened in the early months of the fish's life ; and when 

 we consider the manifold perils, meteorological, physico-chemical and 

 biological, to which the eggs and larvae of a marine animal are subject, 

 it is little wonder that there may be such great differences from one year 

 to another, nor is it a matter for surprise that the precise reasons for good 

 and bad spawning seasons are as yet unknown. 



