308 
IOWA ACADEMY OF SCIENCE Vol. XXIV, 1917 
While these numbers are by no means large enough to be 
conclusive, yet in the face of the conflicting evidence from other 
sources it would seem that the male has no significant effect upon 
the litter number. Such conclusion seems just on logical grounds 
in spite of the possibilities suggested earlier in the paper, and 
until more definite evidence is adduced it seems only, reasonable 
to conclude that the female determines the number at a, birth. 
Kansas Agricultural College. 
LITERATURE CITED. 
EWART, J. C., The Breeding and Origin of Domestic Animals: 27th 
Report Bureau of Animal Industry, pp. 125-186, 1910. 
HARRIS, J. A., Variation, Correlation, and Inheritance of Fertility in 
the Mammals: American Naturalist, Vol. 50, pp. 626-636, 1916. 
RIETZ, H. L., and ROBERTS, E., Degree of Resemblance of Parents 
and Offspring with Reference to Birth as Twins for Registered 
Shropshire Sheep: Journal of Agricultural Research, Vol. 4, pp. 
479-510, 1915. 
WENTWORTH, E. N., and AUBEL, C. E., Inheritance of Fertility in 
Swine: Journal of Agricultural Research, Vol. 5, pp. 1145-1160, 1916. 
