HARDWICKE'S SCIENCE-GOSSP. 



197 



uninhabited islands, birds do not exhibit those 

 symptoms of fear at the approach of man which they 

 commonly show in densely populated localities. It 

 is maintained that this fear is not natural, but has 

 been handed down from generation to generation, 

 and when so transmitted, it is manifested on \\\q first 

 instance of men's approach, and without any pre- 

 vious experience of any of the disagreeable conse- 

 quences thereof. Is it possible that the Petrel has 

 come to regard ships as security against the dismal 

 consequences of storm and tempest ? Sometimes, 

 indeed, the birds are captured and killed by the 

 sailors ; but even that apparently deterrent influence 

 does not seem to divest them of their well-known 

 partiality for ships. Their progenitors have sought 

 and obtained food and shelter from them ; and this 

 experience, being transmitted hereditarily to their 



ternate elevation and depression of the hull as it rides 

 on the crest of a billow or sinks into the trough of the 

 sea, the progressive movement through the force of 

 the gale, and the general indications of bustle and 

 animation exhibited thereby, may perhaps furnish a 

 fund of pleasurable entertainment to the birds which 

 love to live on the ocean. 



We may endeavour to discover the cause of the 

 peculiar sea-walking habits of this genus, whence 

 they have derived their distinctive appellation of 

 Thalassidroiiia. Whilst engaged in this operation, 

 are they in quest of food, or is that the sole aim ? 

 Most naturalists incline to the affirmative answer ; 

 but with all due deference to their opinion, I am 

 constrained to suspect that this is not the only reason 

 for this course of conduct. We know that an abun- 

 dant supply of Mollusks, Radiata, Fishes, Crustacea, 



^^ /:-s^m\m'^i 



Fig. 156. Wilson's Petrel {Thalassidroiiia Wilscnii). 



offspring, induces them to cling to a course of con- 

 duct of the risk and danger of which their own 

 career furnishes no indication. 



Again, if we take into account the indubitable 

 act, that many of the lower animals, especially the 

 Bird tribe, manifest an unequivocal sense of enjoy- 

 ment in activity, we may perhaps be induced to 

 consider that the Petrels regard the motion of a ship 

 as a source of this pleasurable animal excitement. 

 We know that the sciisori motor system of nerves is 

 especially developed among the Birds : and we might 

 thence conclude that they derive a large proportion 

 of their pleasure from its operation. A kitten pur- 

 suing a rolling cork, or ball, furnishes us with an 

 illustration of this phenomenon among the Mammalia. 



The spectacle of a ship in full sail is a source of 

 nervous excitement of a pleasant description. The al- 



and Zoophytes, may be readily found in the Sargasso 

 Sea, and other detached masses of sea-wrack, which, 

 borne up by their air-bladders, perpeuially float upon 

 the surface of the Atlantic Ocean. Why do not the 

 Petrels satisfy their requirements there, and not 

 commit their slender bodies to the fury of the winds 

 and waves? A satisfactory explanation of this point 

 is perhaps impossible ; but I apprehend that the 

 animal delight in excitement already alluded to in 

 the preceding paragraph, and the sources whence it 

 springs, will furnish at least a subsidiary clue 

 towards the elucidation of the sea-walking habits. 



The contemplation of the little sea-birds, whose 

 habits, &c., we have been engaged in discussing, is 

 profoundly interesting to the human heart. Their 

 appearance in the vicinity of ships is regarded by 

 sailors as indicative of a coming storm, with all the 



