TUNNIES AND THEIR RELATIONS 



as far as we are able the method which nature employs 

 in the best of all swimmers. In their case, as in ours, 

 the essential motor is behind, and the body is con- 

 structed in such a way as to offer a series of slippery 

 planes which the water strikes against but does not 

 cling to. 



The animals which swim best, most quickly, and 

 for the longest space of time, are the Cetaceans of 

 medium size. They are the dolphins and porpoises, 

 sometimes called sea-pigs, 1 whose length, less than that 

 of gigantic whales like the cachalots, is seldom more 

 than six or eight feet. Travellers by sea often have an 

 opportunity to see them. By racing alongside and 

 often travelling faster than the ship, they provide a 

 diversion for the passengers on a long and tedious 

 voyage. Sometimes they are seen in couples, male 

 and female, sometimes singly, more often in companies 

 or " schools ". As soon as one arrives, the others 

 come too. We see them a little way off, showing not 

 the slightest sign of fear, exposing, at regular intervals, 

 their curved, shining backs, diving, coming up, diving 

 again and reappearing in a continual repetition of the 

 same undulating movements. They keep alongside 

 the ship, never allowing themselves to be outdistanced. 

 They swim in a series of bounds, and their course, if 

 followed by a pencil on paper, would appear a series 

 of waves. Sometimes these occasional companions 

 follow the ship hour after hour, now drawing nearer, 

 now going farther away, or hastening from one side 

 of the ship to the other. Sometimes they fall back 

 for a time, or disappear, only to return in a little while, 

 but not leaving the neighbourhood of the ship. What- 

 ever the speed of the ship, they accommodate their 

 own speed to it, never giving way. 



Several years ago, the sardine fishermen in a little 

 Mediterranean port found almost every day that their 



1 The French word marsouin is an adaptation of the German Meer- 

 schwein. 



22 



