352 THE BIOLOGY OF THE SEASONS 



hatched. Then a chemical change in the white of egg 

 dissolves the horny shell along a line of weakness at one 

 end, and the young fish emerges. Those mermaids' purses 

 thrown up on the shore are usually emptied egg-shells, as 

 the opening at one end shows. 



The birds among the jetsam are often of great interest 

 even of biological interest . Thus the large number of young 

 guillemots and razorbills in Summer suggests the mortality 

 incident on the first plunge from the rocks. It is the first 

 step that costs, but in some cases the natural mortality is 

 artificially exaggerated by salmon-nets, in which many 

 marine birds get entangled and drowned. It is interesting 

 in another connection to find the stranded bodies of puffins 

 in the winter-time, when there is not a puffin to be seen on 

 any part of the coast for hundreds of miles. These bodies 

 have been washed in from the open sea, where many of our 

 Northern puffins seem to spend the winter months. And 

 he must be dull indeed who experiences no thrill in finding 

 among the seaweed on a winter day a rarity like the wedge- 

 tail petrel, a distinctively pelagic bird, killed perhaps by 

 flying against a ship, and probably washed in from a great 

 distance out to sea. 



What a variety of biological impressions we gain from 

 this walk among the shore-jetsam. There is sometimes an 

 overmastering impression of the abundance of life. When 

 we see the stranded fleet of jelly-fishes, scores of squids in one 

 small bay, zoophytes to fill a sack with, a litter of sea-mats, 

 hundreds of fragile heart -urchins, and so forth, we return to 

 the old image that life is a stream that is always overflowing 

 its banks. 



Nor can we walk along the shore looking at the jetsam 

 without being impressed with the variety of different kinds, 

 as well as with the uncountable number of individuals. 

 Even if we do nothing but gather shells (on a good shore for 



