Feb. 17,1923 
Inheritance in Swine 
579 
While this does not agree exactly with the previous results, still no 
pair is further than two places from its original rank, and, in general, 
the order is similar. 
RELATION BETWEEN NUMBER OF MAMMAE AND ASYMMETRICAL VARIATIONS 
To determine the relation between the number of mammae and the 
frequency of the suppressed nipple or the triangle variations, the animals 
were grouped as shown in Table XI. Twelve animals possessed both 
variations and are counted twice. 
Table XI .—Relation between number of mammae and frequency of suppressed nipple 
Pair No. 4 - 
Pair No. s* 
Pair No. 6. 
Pair No. 7. 
Pair No. 8. 
Pair No. 9. 
Number of animals of each 
class with all even pairs of 
mammae. 
2 
26 
42 
51 
5 
O 
Per cent. 
IOO 
96-3 
Si* 8S 
36.43 
11.36 
Number of animals of each 
class with triangle. 
21 
68 
20 
2 
Per cent. 
25-93 
48.59 
47-5 
67 
Number of animals of each 
class with suppressed mam¬ 
mae. 
I 
18 
21 
19 
Z 
Per cent. 
3-7 
22. 22 
15-0 
45 - 45 
33 
The increased percentage of animals with two types of variations 
among the animals with a larger number of mammae speaks for itself. 
inheritance of the two forms of variation 
Nothing could be learned in regard to this point from these data 
because of the smallness of numbers and because the only boars with 
any considerable number of offspring—the second wild boar and the 
boar of the Berkshire X Duroc Jersey cross—lacked both variations. 
The only female having a very large number of offspring—the F x Duroc- 
Jersey sow—possessed the suppressed mammae herself, but produced 
some offspring having an even pattern, others having a triangle, others 
with a suppressed mammae, and others with both variations when mated 
to her son with an even pattern, and still others with a triangle when 
mated to a Berkshire boar whose pattern is not recorded. 
rudimentary mammae to the rear of the inguinal pair 
The possession of this pair of mammae which is low upon the scrotum 
of the male or upon the inner part of the rear thighs of the female, has 
been described ( 21 ) as a sex-limited character due to a factor which is 
dominant in males but recessive in females, and as a sex-linked char¬ 
acter ( 22 ) for which the male is the simple X sex. However, it appears 
that the latter interpretation is faulty in view of certain data presented 
in the original article ( 22 ) in which this interpretation was advanced. 
These data are those which show that there resulted from the mating 
of boars with rudimentaries to sows with rudimentaries, offspring in 
the ratio of two boars possessing rudimentaries to one female possessin 
