670 REPORT — 1897. 



Miiller have rejoiced to see such facilities for the close investigation of the animal 

 life of the sea ! The English-speaking nations have taken their fair share of the 

 splendid work done at Naples, and it is pleasant to remember that Darwin sub- 

 scribed to the first fund, while the British Association, the University of Cambridge 

 and the Smithsonian Institution have maintained their own tables at the station. ^ 

 The material support thus given is small when compared with the subsidies of the 

 German Government, and not worth mention beside the heroic sacrifices of the 

 Director, Dr. Anton Dohrn, but as proofs of lively interest in a purely scientific 

 enterprise they have their value. Marine stations have now multiplied to such a 

 point that a bare enumeration of them would be tedious. Fresh-water biological 

 stations are also growing in number. Forel set an excellent example by his in- 

 vestigation of the physical and biological phenomena of the Lake of Geneva. Dr. 

 Anton Fritsch of Prag followed with his movable station. There is a well- 

 equipped station at Plon among the lakes of Holstein, and a small one on the 

 Miiggelsee near Berlin. The active station of Illinois is known to me only by the 

 excellent publications which it has begun to issue. France, Switzerland, Sweden 

 and Finland all have their fresh-water biological stations, and I hope that England 

 will not long remain indifierent to so promising a sphere of investigation. 



Biological work may answer many useful purposes. It may be helpful to in- 

 dustry and public health. Of late years the entomologist has risen into sudden 

 importance Dy the vigorous steps taken to discourage injurious insects. I have 

 even known a zoological expert summoned before a court of law in order to say 

 whether or not a sword-fish can sink a ship. I would not on any account run 

 down the practical applications of Biology, but I believe that the first duty of the 

 biologist is to make science, and that science is made by putting and answering 

 questions. We are too easily drawn off" from this, which is our main business, by 

 self-imposed occupations, of which we can often say nothing better than that they 

 do no harm except to the man who undertakes them. There are, for example, a 

 wood many lists of species which are compiled without any clear scientific object. 

 We have a better prospect of working to good purpose when we try to answer 

 definite questions. I propose to spend what time remains in putting and answering 

 as well as I can a few of the questions which occur to any naturalist who occupies 

 himself with life-histories. Even a partial answer — even a mistaken answer is 

 better than the blank indifference of the collector, who records and records, but 

 never thinks about his facts. 



The first question that I will put is this : — Why do some animals undergo 

 transformation while others do not ? It has long been noticed - that as a rule 

 fresh-water and terrestrial animals do not go through transformation, while their 

 marine allies do. Let us take half-a-dozen examples of each : — 



Fluviatile or terrestrial. 

 Without transformation. 



Crayfish. 



Earthworm. 



Helix. 



Cyclas. 



Hydra. 



&c. 



Marine. 

 With transfonnation. 

 Crab. 



Polygordius. 

 Doris, ^olis. 

 Oyster. 



Most Hydrozoa. 

 &c. 



We get a glimmer of light upon this characteristic difference when we remark 

 that in fresh-water and terrestrial species the eggs are often larger than in the 

 allied marine forms. A large egg favours embryonic as opposed to larval develop- 

 ment. An embryo which is formed within a large Qg^ may feed long upon the 

 food laid up for it, and continue its development to a late stage before hatching. 

 But if there is little or no yolk in the egg, the embryo will turn out early to shift 

 for itself. It will be born as a larva, provided with provisional organs suited to 

 its small size and weakness. Large eggs are naturally fewer than small ones. 



' To this list may now be added the University of Oxford. 



2 Darwin, Origin of Specie?, chap. xiii. ; Fritz Miiller, FUr Darwin, chap. vii. 



