Mr Heape, Notes on the Proportion of the Sexes in Dogs. 151 
a higher proportion of males than the Terriers (compare 
Table III). It is also found that both support the view that 
there is almost regular correlation between the number of pups 
of the average litter for each breed and the size of the dog pro- 
ducing it ; the larger dogs producing the larger litters. 
Thus it would seem to be true that a bigger proportion of 
males is produced in the larger litters, or, as stated above, that 
large dogs have a racial tendency to produce an excess of dog 
pups. 
It is suggested that the rate of fertility in different breeds is 
probably coincident with the degree of their specialisation from 
the parent type. 
The annual returns for all breeds dealt with in the Kennel 
Register (Table Y) show a remarkable regularity both in the 
proportion of the sexes born and in the fertility per litter. 
The popular belief that there is a tendency to prolonged 
gestation when the embryo is of the male sex is strongly supported 
by the Schedule returns, in which it is shown (Tables VIII and IX) 
that prolonged gestation is clearly associated with a greatly in- 
creased proportion of male pups born. The size of the litter has 
apparently nothing to do with the length of gestation. 
The tendency of individual male or female parents to produce 
a marked proportion of offspring of one sex, is examined (Table X). 
It is seen that bitches which are concerned in the production of 
four or more litters show a much higher percentage of variability 
than sires, but that the sire may exert influence is clear from the 
Mastiff records. 
Details supplied by Basset hound and Dachshund Schedules 
give some support to the popular belief that seasons affect the 
proportion of males and females born ; the figures available, 
however, are far too small to allow of a trustworthy test being 
made. 
I wish to acknowledge my great indebtedness to the following 
gentlemen for the valuable records of their experience as breeders, 
with which they have been kind enough to supply me : 
Mr C. H. Backhouse, Mr R. M’M. Bolster, Mr E. Brough, 
Mr W. T. Cotton, Mr H. G. B. Eaden, M.D., Mr Fred Edge, 
Mr W. Flett, Mr C. E. Frost, Mr G. Jamison, Captain T. Keene, 
Mr J. McWatt, M.D., Sir Everett Millais, Mr A. O. Mudie, 
Mr C. C. Rice, Colonel Le Gendre Starkie, Mr J. Sumner, 
M.R.C.V.S., Mr S. Vale, Mr H. Vine, Mr Alfred Weaver, 
Mr J. L. Winchell, Mr J. Young. 
