of Fingers and Toes, and of the Phalanges, in Man. 105 
additional thumb. Three of the seven external cases were 
on feet, on the outer side. Inthe hereditary group, taken as 
families, it is on the inner side in the majority of the cases. 
In one family only [cases 17, 17 (a), 18 (a)] does it affect 
the big toes. As far as these cases show, it would, there- 
fore, seem to be more common on the outside of the foot, 
and, on the hand, more frequent on the inner than the outer 
side. Were we to connect these facts with the facts regard- 
ing the order in which the toes appear, or disappear, among 
the mammalia, we would require to consider not only the fact 
that the inner digit is the last added, but that the increase, or 
_ decrease, takes place alternately on the inner and outer sides. 
On the hand, the additional digit was smaller than the 
next, always soin the case of an additional little finger, 
and nearly always so in the case of an additional thumb, 
but in case 18 (a) the two thumbs were equal, and in case 2 
nearly equal. On the foot, in cases 12 and 198, the sixth 
toe is thicker than the fifth, although it has a phalanx less, 
but the thickness does not seem to depend on the bones. 
Among the hereditary cases, in case 17 (a) the internal of 
the two great toes is the larger. 
Cases of non-hereditary increase in the number of the 
digits appear to be of not unfrequent occurrence. Most 
surgeons have met with cases, and it is a common practice 
to remove the additional digit early. The above cases show 
that the removal of the digit, in cases in which it is in- 
herited, does not eradicate the atavic influence. But most 
of the cases of original variation do not appear to transmit 
the tendency, for, besides the facts mentioned in some of 
the cases, cases of original variation are much more common 
than hereditary cases, even reckoning each member of the 
existing family as a separate case. 
Hereditary Transmission of the Variety.—The transmission 
of a newly acquired variety has to depend on whether the 
new influence or the prior normal influence proves the 
stronger; and, if the former prevails, it has, so long as 
only one parent presents the variety, farther to depend for 
its continuance on its chance of the fact that one parent 
may exert more influence than the other on some of the 
young. Thus if not itself at the beginning overcome by 
NEW SERIES.—VOL. XVIII. NO, I.—JULY 1863. 0) 
