Oct. *7, 19*3 
Otocephaly in Guinea Pigs 
175 
Table VII. —A comparison between the mortality figures in Family 13 and the other 
families which produced otocephali 
Normal litter mates of otocephali. 
Normal stbs, not litter mates of otocephali. 
Raised. 
Died. 
Bom 
dead. 
Bom 
alive. 
Raised 
of bom 
alive. 
Raised. 
Raised. 
Died. 
Bom 
dead. 
Bom 
alive. 
Raised 
of bom 
alive. 
Raised. 
Num¬ 
ber. 
34 
39 
Num¬ 
ber. 
21 
5 
Num¬ 
ber. 
20 
16 
Per 
cent. 
73-3 
73-3 
Per 
cent. 
61.8 
88.6 
Per 
cent. 
45 * 3 
65.0 
Num¬ 
ber. 
244 
195 
Num¬ 
ber. 
78 
51 
Num¬ 
ber. 
96 
40 
Per 
cent. 
77 -o 
86.0 
Per 
cent. 
75-8 
79-3 
Per 
cent. 
58.4 
68. % 
Family 13. 
Others.... 
Table VIII .—The number raised , dying between birth and 33 days , and born dead , and 
the per cent born alive , raised of those born alive, and raised to 33 days, among the litter 
mates of the otocephali a 
Normal litter mates of otocephali. 
Normal sibs, not litter mates of otocephali. 
Size of litter. 
Raised. 
Died. 
Bom 
dead. 
Born 
alive. 
Raised 
of bom 
alive. 
Raised. 
Raised. 
Died. 
Bora 
dead. 
Bom 
alive. 
Raised 
of bom 
alive. 
Raised. 
1.... 
Num¬ 
ber. 
Num¬ 
ber. 
Num¬ 
ber. 
Per 
cent. 
Per 
cent. 
Per 
cent. 
Num¬ 
ber. 
23 
Num¬ 
ber. 
7 
Num¬ 
ber. 
XI 
Per 
cent. 
Per 
cent. 
76. 7 
82.5 
81.3 
68.9 
69.0 
60.0 
Per 
cent. 
56. X 
70.6 
70.6 
a. 
18 
x 
95-6 
83.6 
52*8 
8 5 - 7 
69.6 
67.9 
81.8 
58.2 
35-8 
8*6 
86.9 
3... 
- 
178 
82 
. „ . 
10 
* 
9 
s.*. 
9 
9 
5 
37 
18 
2 
27 
68. 2 
5 1 * 3 
6. 
c 
j 
80.0 
xoo. 0 
80.0 
83-3 
* 
** 
50* ° 
Total. 
Probable error 
of total. 
73 
26 
36 
73-3 
2.6 
73*7 
3 * 0 
54 -1 
2.9 
439 
129 
136 
80. 7 
1* 0 
77*3 
1, a 
62.4 
x* 2 
. a If the percentages for the normals which were not litter mates are weighted by the number in each 
size of litter among the litter mates, we get 81.6 per cent bom alive, 77.2 per cent raised of those bom alive, 
and 6a.j per cent raised, figures which do not differ appreciably from the actual percentages. 
BIRTH WEIGHT 
Unfavorable conditions naturally have a great influence on birth 
weight. The average birth weight of otocephali, their litter mates, 
and their brothers and sisters which were not in litters containing otoce¬ 
phali are given in Table IX. Because of the very important effect of 
size of litter on birth weight, a correction must be made in order to make 
valid comparisons. The correlation between birth weight and size of 
litter (individual the unit) came out —0.41, —0.60, and —0.58 in these 
three classes of young. The regressions of weight on size of litter de¬ 
duced from these figures are —8.2, —11.1 and —10.4 gm. per unit 
difference in size of litter. All average birth weights were adjusted to 
an average litter of three by use of the regression of —10.3. 
