12 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



example of some principle of Biology, not only does it 

 add to their gratification but I am sure has considerable 

 educational influence by opening their minds to new 

 realms of thought, new methods of questioning nature. 



For example, if a boy brings us a light-coloured shanny 

 caught in a shallow exposed pool, we can place the little 

 fish in a deep vessel in semi-darkness under a table, or 

 cover it with some brown sea- weed, the result being that 

 when the boy comes next day to look for his specimen, he 

 has been known to exclaim, " Hullo ! where is my 

 shanny? There is only a black one here." It is then 

 easy, by putting the fish into a shallow white dish in the 

 bright sunlight, in a short time, to turn the black shanny 

 into what he recognises as the light-coloured one he 

 caught. You can then tell him of the beautiful pigment 

 cells of the skin and show them to him under the micro- 

 scope in a small living fish, in a watch-glass full of sea- 

 water. You can show him a speckled shrimp hiding in 

 sand and a mottled shrimp in gravel, and the little prawn 

 Virbius which may be almost any colour according as you 

 change its surroundings from green to red or to dark 

 brown sea- weeds. You explain the difference in pig- 

 mentation on the upper and lower sides of a flat fish, you 

 remind him of the Chamaeleon, tell of Sir Joseph Lister's 

 observations on the change of colour in the skin of the 

 Frog, and — most beautiful experiment of all — show him 

 the " blushing " of the newly-born cuttle-fish. From this 

 there opens up a wide range of physiology, of the influence 

 of light and the controlling action of nerves, not to 

 mention natural selection and evolution in general. 



This is only one of many examples that might be taken. 

 Almost any of the common marine animals, if carefully 

 watched as to structure and habits, show us interesting- 

 cases of adaptation to their surroundings and mode of life. 



