196 



HARDWICKE'S SCIENCE -GOSSIP. 



secondary quills are ferminated with traces of the 

 same colour. The tail is square, and the tips of the 

 wings hardly reach beyond its extremity. The total 

 length of this interesting bird is ^h inches. 



Having specified the various characteristic features 

 of the British department of this interesting genus 

 of sea-birds, I shall now briefly discuss some ques- 

 tions that may be readily started upon the contempla- 

 tion of their habits. In the first place, we may 

 observe that the extraordinary vital energy and 

 endurance exhibited by these tiny creatures may 

 reasonably excite feelings of wonder, and demand 

 some explanation. During stormy weather these 

 petrels have been observed to follow in the wake of 

 a particular ship for as long a period as one month. 



instrumentality of the oxygen contained in the red 

 corpuscles of the same fluid. Now it follows, that 

 the more thoroughly the blood is charged with these 

 nerve-building materials and with oxygen, the more 

 efficient and inexhaustible will be the supply of nerve 

 or animal force. Perhaps the fresh air of the sea 

 and the character of the Petrel's food furnish power 

 to the nervous centres which mniister to the digestive 

 apparatus of the bird so thoroughly and efficiently as 

 to enable it to digest and assimilate nutritive ma- 

 terials in a manner which other birds, differently 

 situated, cannot experience. Moreover, we know 

 that the stomachs, both of the Stormy and Wilson's 

 Petrel, are exceedingly large in proportion to the 

 size of the birds. There are two gizzards provided 



Fig. 154. The Vv.]m:>.r V&\.rtA{P!VCe!',a?-ia g!ncial/s). 



During this time there is exhibited on their part an 

 almost perpetual fluttering of the wings and exertion 

 of the feet — a restless spontaneity of movement that 

 necessarily involves an immense expenditure of 

 animal energy. Now, from what source springs the 

 fuel that feeds this vital machinery ? Let us imagine 

 a man who is compelled to exercise. the muscles of 

 his limbs incessantly every day, say for a period of 

 twelve hours. Would his frame, however naturally 

 robust, endure this treatment for any lengthened span 

 of time ? But the Petrel, in addition to this exten- 

 sive and protracted limb-movement, is known to 

 emit during the night-time its jjeculiar melancholy 

 cry. Perhaps the incessant inhalation of the exhila- 

 rating air of the sea imparts to the nervous centres of 

 the bird an energy and efficiency which men, living 

 amid the smoke and foul air of cities and houses, can 

 never experience. Physiologists inform us that the 

 blood, being charged with certain ingredients, builds 

 up the structure of the nervous centres, imparting 

 thereto at the same time a store of potential energy 

 which, at the command of the will, &c., is dis- 

 charged or converted into actual energy through the 



Head and foot of the Stormy Petrel {T/ialassi- 

 droina pelaglca). 



with a great number of glands, which secrete 

 gastric juice, and they are curved in a very 

 peculiar manner. The Petrels also subsist 

 chiefly on fishy and oily matter, a species of 

 nutriment which, in the human subject at 

 least, is eminently adapted to the maintenance 

 and stability of cerebral and nervous tissue. 

 In the next place, we may institute a brief inquiry 

 regarding the cause of the manifest predilection for 

 ships exhibited by the members of the Petrel tribe. 

 Why do these birds follow ships for so lengthy a 

 period ? Some naturalists suppose that the hull of 

 the vessel shelters their tiny Ijodies from the violence 

 of the storm. Others think that the keel of the 

 ship, in its motion through the water, ploughs up 

 sundry mollusks, &c., and that the birds love to take 

 advantage of this convenient provision for their 

 bodily sustenance. In attempting to solve this diffi- 

 culty, we must remember that the Petrels appear in 

 the vicinity of ships only during stormy weather. 

 But the turbulence of the seas at that period would, 

 we might apprehend, be amply competent to stir up 

 these marine animals to the surface, without the 

 intervention of a ship's motion. The latter theory 

 would, therefore, on this view of the matter, appear 

 to be untenable ; and on that account let us endeavour 

 to contemplate the subject from a different stand- 

 point. Latter-day physiologists have propounded 

 the theory of the hereditary transmission of acquired 

 psychical aptitudes. We know that upon desert, 



