3/6 MAINE AGRICUIvTURAL EXPERIMENT STATION. igi2. 



by some one. Personally, however, I am more inclined to keep 

 to the solid ground of the observed physiological peculiarities of 

 tnese matings rather than to 'juggle the genes.' Even in the 

 hands of an adept in this direction, which the writer cannot 

 claim to be, the latter procedure runs some risk of taking one a 

 great way from any solid ground of fact whatever. 



Regarding these four matings 699-702 the following facts are 

 definitely known : 



1. High fertility of eggs. 



2. Smallest embryonic (pre-natal) mortality of any particu- 

 lar gametic combination yet experienced in the w^ork of this la- 

 boratory. 



3. Great vigor and vitality of chicks at hatching and during 

 growth. 



4. Very low chick and adult mortality. 



5. A higher egg production in practically all adult daughters 

 than would be expected from the gametic constitutions per se 

 of the parent forms, the latter being definitely known from their 

 pedigrees and from their behavior ( $ 578), or that of their 

 full sisters in other t3^pes of matings.. 



I cannot escape the conviction that in some way the first 

 four of these facts are connected with the explanation of the 

 fifth. There the matter must be left for the present. 

 - This case points to the importance of the physiological study 

 of individuals in genetic work involving crossing. .Onty the most 

 superficial aspects of this subject have ever been touched. The 

 'increased vegetative vigor' of first crosses is clear in some 

 instances, but very far from being so in others, and nobody has 

 ever shown by a clean-cut physiological investigation why or 

 how the phenomenon occurs. Every breeder of experience 

 knows that this is but one of many interesting and fundamen- 

 tally significant physiological matters in connection with hy- 

 bridizing and cross-breeding which need investigation. The 

 animal breeder knows further that there are real objective phe- 

 nomena, and not mere idle superstitions of the fancier at the 

 basis of those things which the latter calls 'nicking' and 'prepo- 

 tency,' for example. No doubt these things depend on simple 



