DEAD IN SHELL 298 
increase, one may ask what is the cause of bad fertilising ? It 
may be due toa variety of causes, but more especially because of 
bad mating, breeding from young pullets, or immature cockerels. 
But there is, I think, another and a deeper reason for bad 
fertilising, and that is the great growth of inbreeding in modern 
times. During the last ten or fifteen years inbreeding in the most 
direct manner has become so common that nearly all the com- 
moner breeds of fowls in England are more or less closely inter- 
related. We talk about infusing “new blood” into our stock, 
but where are we to get it? Certainly not in England, excepting 
by some remote chance that cannot be foretold. We are all up 
to the neck as it were in Cam and Barron, Hunter and Collinson 
blood, and it is almost impossible to get away from it. Even 
if we send to America or Australia or South Africa or Holland for 
the male birds there is no guarantee that they are not inter- 
related to our stock, although the chances are that they will be 
far enough removed in relationship from our birds that no physical 
deterioration will take place. The increase of dead in shell is 
contemporaneous with the passion for inbreeding that has swept 
over England like a plague. I do not suggest that a certain 
amount of inbreeding is not necessary to get the high fecund 
strains, but I think the time has arrived when the warning signal 
has been hoisted and that we dare not continue the practice 
without let or hindrance for any appreciable time. 
If my argument be correct—and I only put it forward as a 
suggestion—the weak-germ theory is only a half truth, the real 
truth being that the weak germs, which result in dead in shell, are 
caused by a certain physical deterioration which is the result of 
excessive inbreeding. 
