94 



THE ZOOLOGIST. 



opponent goes on to illustrate his principle. Now suppose, for 

 instance, the gills of an aquatic animal converted into lungs, 

 while instinct compelled a continuance under water, would not 

 drowning ensue ? No doubt, answers the Darwinian ; yet we 

 see that young Frogs do not keep their heads under water after 

 ceasing to be tadpoles. The case of the Climbing Perch (Anabas 

 scandens) also seems adverse to Darwin's theory. 



Darwin lays hold of the Lamarckian doctrine of use and dis- 

 use, and shows how certain birds (as the Apteryx and Ostrich) 

 may have by Natural Selection lost the use of their wings as 

 organs of flight. He further treats of the curious instances in 

 which distinct species present analogous variations, and where a 

 variety often assumes some of the characters of an allied species, 

 or reverts to some of the characters of an early progenitor. 

 This is seen in the tendencies of some domestic Pigeons to 

 assume the bluish colour and characteristic marks of the original 

 Eock-Pigeon. The whelp of the Lion sometimes presents stripes, 

 and in like manner the young of the Puma, Tapir, and Wild 

 Pig, and the young of the Blackbird are all speckled. He also 

 illustrates this subject by referring to the occasional presence of 

 stripes on the legs of the various species of the Horse genus 

 (such as the Ass, Mule, Quagga), like those on the Zebra, or 

 stripes on the shoulder, as in the Ass ; and by comparing his 

 examples with the analogous case of the domestic Pigeons he 

 comes to the following conclusion : — " For myself, I venture 

 confidently to look back thousands on thousands of generations, 

 and I see an animal striped like a Zebra, but perhaps otherwise 

 very differently constituted, the common parent of our domestic 

 Horse (whether or not it be descended from one or more wild 

 stocks), of the Ass, the Hemionus, Quagga, and Zebra." 



He sees no difficulty in Natural Selection forming the ex- 

 panded membrane of the Flying Lemurs and Squirrels, but he 

 makes no mention of the Flying Dragon. The flank-membranes 

 of the former are stretched out by the limbs, while the latter 

 has its membrane on its ribs (six). So complex an organ as the 

 eye is accounted for by this Natural Selection and gradual de- 

 velopment. " In living bodies variation will cause slight altera- 

 tions, generation will multiply them almost infinitely, and 

 Natural Selection will pick out with unerring skill each im- 



