154 EVOLUTION AND DISEASE. 
considered as distinct animals, having very distinct 
powers. In order to ascertain this, I took the spurs of 
hen-chickens and placed them on the legs of young 
cocks. I found that those which took root grew nearly 
as fast, and to as large a size as the natural spur on the 
other leg, which appeared to be a contradiction to my 
other experiments. Upon another examination of my 
hens, however, I found that the spurs had grown consider- 
ably, although they had taken several years to do it; . 
for I found that the same quantity of growth in the spur 
of a cock, while on the cock, during one year, was as 
much as that of the cock’s spur on the hen in the course 
of three or four years, or as three or four to one; whereas 
the growth of the hen’s spur on the cock was to that of 
the proper spur of the hen as two to one.” 
When a female animal belonging to a dimorphic 
species assumes male characters, it is truly an example 
of atavism, or development of transmitted characters 
normally latent. 
Before leaving this matter it will be useful to indicate 
to some extent our knowledge as to the frequency of 
the assumption of male characters by the females of 
dimorphic forms. In birds there can be no question 
that very many specimens have been seen and carefully 
studied, but in the case of female deer putting up antlers 
the case is very different. On making inquiries of 
persons likely to have seen such specimens I find it 
extremely difficult to obtain authentic information, and 
many of the statements in circulation on this matter 
have very shallow foundations. One of the most acces- 
sible specimens is preserved in the museum of the Royal 
