n6 The Irish Naturalist. [May, 



REVIEWS. 



The Penycuik Experiments. By J. C. Ewart, M.D., F.R.S. 

 Edinburgh ; A. and C Black, 189S. 10s. 6d. 



The title of Prof. E wart's book convejs little to the ordinary reader of 

 the Irish Naturalist. To some the name even of the small Scotch town — 

 Penycuik — the place which the author has chosen for his experiments, 

 ma}- be unknown But many zoologists and breeders of stock have been 

 watching with keen interest the results of Prof. Ewart's experiments for 

 some years past. Since he first succeeded in mating a zebra with a 

 horse, with the result that a most interesting h3'brid was born, he has 

 secured several others, and has paid particular attention to various 

 problems connected with this subject. 



Though these experiments have no direct connection with Irish 

 natural history, they are of such general interest and importance, that 

 the readers of the Irish Naturalist will welcome a short announcement of 

 the aims of this work. Since several Irish horses, moreover, were used 

 in Prof. Ewart's experiments, an indirect claim actually exists in 

 noticing this little book in our columns. 



In the pages of the Veterinarian and the Zoologist the more important 

 results of the Penycuik experiments have already been fully discussed. 

 However, the form in which the results of Prof. Ewart's interesting 

 experiments are now published, enables the reader to more thoroughly 

 grasp their importance and the methods by which it is desirable that 

 they should be continued by others. 



No less than nine zebra hybrids have been bred by Prof. Ewart by 

 crossing mares of various sizes and breeds with his famous zebra 

 stallion " Matopo." He also reared three hybrids which had zebra 

 mothers, whilst the sire was in one case a donke}- and in two ponies. 



Now, the breeding of these hybrids sheds a new light 011 many 

 questions of general biological interest, such as the origin of stripes, 

 reversion, inbreeding, and prepotency. 



We know very little as yet about reversion. To give a familiar 

 example of what is meant by the term, we cannot do better than quote 

 the author's own words — " It is commonly believed that a child some- 

 times, instead of taking after its father, closely resembles its father's 

 mother, or is the image of its own mother." Some of the hybrids 

 reared by the author, for instance, suggest their zebra sire, others their 

 respective dams; but, curiously enough, even the most zebra-like in form 

 are utterly unlike their sire in the markings. '• It is not a matter of 

 taking after a grand-parent," remarks the author, " but after an ancestor 

 in all probability thousands of generations removed, an ancestor 

 probably far more like the Somali than any of the Burchell zebras." 



