I. 



On some Problems of the Distribution of 

 Marine x'Vnimals. 



1T7HEN Professor Hensen started on his Plankton expedition in 

 Vi 1889, to attack the problem of the " metabolism of the ocean" 

 from a new point of view, and with methods other than had 

 been employed hitherto, he wanted, as is well known, to study the 

 organic life in high seas as free from the influence of coasts as possible, 

 so as to obtain a more accurate conception of the distribution of 

 animals and plants, and to procure a large quantity of material 

 to which no exception could be taken from which to draw conclusions. 

 Of course, he does not believe, as some of his opponents would have 

 one think, that he has determined once and for all, by his captures, 

 the contents of the part of the ocean he passed through ; he merely 

 intended to see what kind of material occurred at that particular 

 time, and Hensen himself is well aware that such complicated 

 problems as are resting in the bosom of the ocean can only be attacked, 

 and -not solved offnand. 



The hypothesis upon which he acted was, that the distribution of 

 organic life, if not influenced by the coasts and the everchanging 

 conditions we observe there, must be sufiiciently constant to enable 

 us to obtain an accurate idea of the contents of the ocean by fishing 

 in more or less limited areas with the help of accurate nets. 



His views were already contested and defended at the time 

 when the question of supplies for the expedition was being discussed, 

 and there were naturalists who, without being quite convinced 

 of Hensen's views as to the uniformity of the marine fauna, were, 

 nevertheless, strong upholders of his plans, saying that such an 

 undertaking as his was worthy of support in any case, as the results, 

 whatever they might be regarding the uniformity of ocean life, would 

 certainly be a large contribution to our knowledge of biological and 

 morphological questions. 



So far as I can ascertain from a relatively small part of the rich 

 material which the expedition l)roughthome (the Craspedote Medusae, 

 which were given to me to work out), this view has, as a matter of 

 fact, proved true. In the bottles entrusted to me, I was able to 

 examine several new and interesting forms, besides many other 

 species not sufficiently characterised at present, and the material, 



