138 Mr Hecvpe, Notes on the Proportion of the Sexes in Dogs. 
I think it must be admitted that the close approximation of 
the total results for each year is very remarkable. The greatest 
variation under the heading dogs per 100 bitches is l 1 98, and 
under pups per litter '06. This yearly comparison is far more 
regular than the yearly records for Greyhounds (Table I), and 
I am disposed to think the reason for this is that the breeding 
time is not artificially controlled to the same extent as we have 
seen is the case for Greyhounds. 
The only breed dealt with in the Kennel Register returns 
which is at all comparable to the Greyhound returns, so far as 
the number of pups is concerned, is Collies and Sheep dogs ” ; 
I have therefore tabulated details of the latter breeds to show 
monthly returns of births, &c. 
The result is given in Table VI and it is seen to be, in some 
respects, different from that obtained from the Greyhound Stud 
Book. 
March to June are the months in which the greatest number 
of births is recorded for Greyhounds, while for Collies most births 
are recorded from May to August. As I have already stated the 
purpose for which most Greyhounds are bred is accountable for 
the period of greatest fertility and it may be assumed that in 
this respect the natural breeding habits of Collies are much less 
interfered with. For the same reason, while for Greyhounds the 
months of August to December show a very low rate of fertility, 
there is no such great variation for Collies at any time of the 
year, though the birth rate from October to December is the 
lowest of the year. 
Thus, while the Greyhound records, years 1886 — 1892, show 
only 65 births in December against 3099 in May, the lowest 
record for Collies, years 1889 — 1891, is 410 births in November 
and the highest 796 in July. 
That the rate of fertility (pups per litter) is not responsible 
for the seasonal variation in the number of Collies born is clear, 
and a glance at the litters will show that, for Collies, there is a 
gradual falling off in the number of litters from the month in 
which most births are recorded to the end of the year, and a 
gradual rise from the beginning of the year to the date of the 
maximum births. 
Concerning the sex of the pups produced. The totals for 
Greyhounds show a proportion of 118 - 5 dogs and for Collies 
118T9, a very close agreement. Not less remarkable is the 
similarity in the difference between the variation of this per- 
centage each year; that for Greyhounds, 1887 — 1890, being 6 
(115—121), that for Collies, 1889—1891, being 7 (115—122). 
It is the monthly returns of the proportion of dogs where the 
greatest difference between the records of these breeds is apparent. 
