The Laws of Heredity. 167 



members from a common ancestor this is called a case of atavism. 

 This is called reversional heredity (Lucas) ; reversion, or in the 

 more expressive German term, Riickschlag and Ruckschritt. 



The fact was known to the ancients; Aristotle, Galen, and 

 Pliny speak of it. Plutarch mentions a Greek woman who gave 

 birth to a negro child, and was brought to trial for adultery, but it 

 transpired that she was descended in the fourth degree from an 

 Ethiopian. Montaigne expresses his astonishment at this, ' Is it 

 not marvellous,' says he, ' that this drop of seed from which we 

 are produced should bear the impression, not only of the bodily 

 form, but even of the thoughts and the inclinations of our fathers ? 

 Where does this drop of water keep this infinite number of forms ? 

 and how does it bear these likenesses through a progress so hap- 

 hazard and so irregular that the great-grandson shall resemble the 

 great-grandfather, the nephew the uncle ? ' 



In the first part of this work are recounted a large number of 

 cases of atavism ; here it will suffice to call attention to some 

 curious facts which will serve to show the tendency of heredity. 



The phenomenon of reversion is of very frequent occurrence in 

 vegetal and animal races. Dr. Broca gives a curious example, the 

 result of an experiment he made with a view to study the formation 

 of races by methodical selection. He took the seeds of corn- 

 flower which he gathered promiscuously in the fields, and sowed 

 them. This produced blue and red cornflowers. He then sowed 

 the seed of the red cornflowers only, and obtained about a hundred* 

 flowers, two thirds of which were blue, the remainder varying from 

 violet to rose colour. If again the seed of the rose cornflower be 

 sown, the result will be a few blue flowers, many red, rose, and 

 even white. It would thus be possible to create a white species, 

 but only by a constant struggle against the phenomena of reversion 

 which persistently reproduce the primitive type. 1 



Girou de Buzareingues gives at length the history of a strain of 

 dogs, a cross between the pointer and the spaniel, which is briefly 

 as follows. In the first generation the product is a spaniel ; this, 

 being crossed with a pure pointer, the result is a mongrel male with 

 all the external characters of the pointer. By coupling this mongrel 



1 Bulletins de la Soalle cT Anlhropologie, 2* serie, tome iv. See Darwin, Vari- 

 a/ion, etc., ch. xiii., for several instances of reversion in plants and animals. 



