SCIENTIFIC METALLURGY AND MINING. Un- 



caused the rapid colonisation of New South Wales, of Victoria, and of 

 New Zealand. Since those early and successful efforts to work the gold 

 deposits of this country there has been a long lull in this industry, and 

 we hope that we are now at the nadir of our decrease. It seems to me 

 that when the improvement does come, it will be in the form, either of 

 the discovery of lodes other than in our gold reefs, or beds other than 

 those of coal, or, as is perhaps more likely, of the successful working of 

 our present low grade ores. It has been stated that the greatest 

 wealth, mineralogically speaking, of a country is to be found in her 

 poorest ores, and though at first sight this may seem a paradox, expe- 

 rience has proved it to be true. In conclusion, let us notice that the 

 success of our educational institutions does not rest entirely with the 

 staff, or even with the students. Unless we have the sympathy of an 

 enlightened public opinion we shall be hampered in our endeavours. 

 We expect, we claim this sympathy, and I believe that in this also, we 

 shall not be disappointed." 



AN EXPERIMENT CONCERNING THE ABSENCE 



OF COLOUR FROM THE LOWER SIDES 



OF FLAT FISHES. 



BY J. T. CUNNINGHAM, M.A., Naturalist to the Marine Biological Association. 

 " Zoologischer Anzeiger," I8th January, 1891, No. 354, p. 27. 



One of the most interesting questions which biological research has 

 still to decide is whether adaptations in organisms are due to the natural 

 selection of indefinite variations or to the definite influence of the 

 conditions of life. One school of evolutionists, that of which Weismann 

 is one of the most eminent leaders, maintains that every character in 

 animals is an adaptation and every adaptation is sufficiently explained 

 by indefinite variation and natural selection. Another school believes 

 that many things are not adaptations and that those characters which 

 are adapted are due to the definite influence of conditions. The former 

 school would I suppose maintain that the whiteness of the lower sides 

 of flat-fishes was an adaptation, and was due to selection. What is the 

 especial advantage of this character to flat fishes I am unable to perceive. 

 But it seems to me more probable that it is due in some way to the fact 

 that little or no light can fall on the lower sides of these fishes, because 

 these sides are generally in contact with the ground. 



The following experiment seems to me to support very strongly the 

 latter views ; it was carried out in the Plymouth Laboratory of the 

 Marine Biological Association. 



At the beginning of last May I received from Mevagissey in Corn- 

 wall a large number of young flounders (Pleuronectes flesus) in process 

 of metamorphosis. They were very transparent and measured 11.5 to 

 12.7 mm in length. In a few the metamorphosis was almost complete 

 the left eye having reached the edge of the head but in the majority the 

 left eye though it had commenced its "migration" was still on the lower 

 side. The little fish had already developed the habit of lying on the 



