1899] E WART'S PENYCUIK EXPERIMENTS 205 



Now it is one of the merits of Professor Ewart's work that he has 

 done much to place the doctrine of reversion on a firmer basis of 

 carefully criticised instances. While Mr. Bateson expressed the views 

 of many when he said — " Around the term reversion a singular set of 

 false ideas have gathered themselves," and that "it would probably 

 help the science of biology if the word ' reversion ' and the ideas 

 which it denotes were wholly dropped, at all events until variation 

 has been studied much more fully than it has yet been," Professor 

 Ewart's cases will certainly tend to reassure the doubtful as to the 

 reasonableness of the reversion interpretation. 



Just as von Baer made the chick pre-eminently the bird of the 

 embryologist, so Darwin made the pigeon pre-eminently the bird of 

 the biologist, and Professor Ewart gives it the first place in his 

 systematised record of experiments. The most striking case is the 

 following : — A pure white fantail cock, which in colour proved to be 

 prepotent over a blue pouter, was mated with a cross previously made 

 between an owl and an archangel, which was far more of an owl than 

 an archangel. The result was a couple of fantail-owl-archangel 

 crosses, one resembling the Shetland rock-pigeon, and the other the 

 blue rock of India. Not only in colour, but in form, attitude, and 

 movements there was an almost complete reversion to the form which 

 is believed to be ancestral to all the domestic pigeons. The only 

 marked difference is a slight arching of the tail. The one parent, a 

 white fantail, belongs to an old-established breed ; the other parent, an 

 owl-archangel cross, had already more or less lost the characters of the 

 relatively recent archangel, and had begun to revert towards the blue 

 rock ; the progeny of the two was a practically complete reversion. 

 The interpretation suggested is that the older and more stable 

 ancestral units assert themselves successfully in the germinal struggle, 

 while the newer features attain no development. 



A few other examples may be noted. An Indian game Dorking- 

 cock, crossed with a dark bantam hen, produced amongst others a 

 cockerel almost identical with a jungle fowl (Gallus banhiva), i.e. with 

 the original wild stock. 



A smooth-coated white rabbit, derived from an Angora and a 

 smooth-coated white buck, was "mated with a smooth-coated, almost 

 white doe (granddaughter of a Himalaya doe), with very interesting 

 results, significant of the complexity of the conditions. In the litter 

 of three, one is the image of the mother, one is an Angora like the 

 paternal grandmother, and one is a Himalaya like the maternal great- 

 grandmother. 



Again, the Burchell zebra-horse hybrids are in their markings very 

 unlike their zebra sire or dam, but bear distinct resemblance in their 

 stripes to the Somaliland zebra (Eqims grevyi), which the author regards 

 as, in its markings at least, the most primitive of all living zebras. 

 But the evidence from pigeons and rabbits seems stronger than this. 



