ON HABITS OF OBSERVING. 37 



though for a long time this was never suspected.* 

 Again, when first it was observed that the natatorial 

 birds had webbed feet, doubtless there was a feeling 

 that this structure and the power of swimming went 

 always together ; yet every tyro now knows that 

 there are birds with webbed feet which never swim, 

 as there are others, in which the toes are divided to 

 their origin, which swim admirably. In fact, num- 

 berless are the cases in which we find a deviation 

 from some general rule. Nature seems to delight in 

 the production of apparent anomalies, for the ex- 

 press purpose of baffling our attempts to bind her by 

 the fetters of a preconceived system. These are for 

 a while so many stumbling-blocks in our way, which 

 we as little expect to meet with beforehand, as we 

 are prepared to explain them when they occur. 

 There are some facts, indeed, of this kind so extra- 

 ordinary, that had they been recorded formerly, 

 when correctness in observing was less attended to 

 than at present, and had they rested only on such 

 statements, they would not now be received. And 

 some which were so recorded, and for many years 

 disbelieved on account of their strangeness, have 

 been observed again in modern times, and to the 

 surprise of naturalists, been proved true.f From 

 these circumstances we learn caution, as well in pro- 

 nouncing any fact in itself to be true or false, as in 



* See Duvernoy and Lerebouillet on the organs of respiration in 

 the Crustacea Isopoda in the Ann.des. Sci. Nat. Ser. iii. torn. xv. p, 1 77. 



f As an instance in point, we may mention the fact of some of 

 the great serpents in India incubating their eggs. See a note 

 on this subject in our edition of White's Selborne, Lett. xvii. to 

 Pennant. 



