PEDIGREE INHERITANCE. 
41» 
bitch puppies. The regulation of the sexual ratio in the domestic animals 
would become important from the breeders’ point of view. 
The application of the idea of the «Pedigree Inheritance» renders 
the distinguishing of mono-, di- and poly hybrid crosses, and the troublesome 
mathematical operations with the pairs of factors, superfluous. In this — 
irrespective of, as I think I pointed out, the most proximate and most 
probable natural cause of the heredity — I, for my part, see a practical 
advantage, partly, because in fact it is scarcely possible to decide about 
the properties crossed, and the more these are to be crossed, which are unit 
and which are complex, and, chiefly, because it is doubtful whether the 
factors exist at all ; and it can hardly be supposed that the very number 
of the pairs of factors which are at work in the single cases, in the single 
details of heredity, could be exactly proved. Knowing the origin 
and composition of the breeds, knowing the qua¬ 
lities of the individuals — and of their ancestors — 
which are intended to be crossed, or, knowing, in 
a word, their pedigrees, the probable hereditary 
ratio can be taken into account beforehand, being 
nothing else than the proportion of the properties 
of the ancestry, which can be traced to the pedigree. 
Consequently it is clear that the single properties 
are inherited separately in some of the ea s es, and 
collectively in others, or, partly separately and 
partly collectively in still otlie r\s. 
From the pedigree the inheritance, and from 
the inheritance the pedigree can be guessed. 
The writer also thinks that in all the ways which can be imagined, 
the most probable is, that the phenomenon of inheritance is caused by such 
or similar infinitely complicated processes as are pointed out by Darwin’s 
Hypothesis of Pangenesis, and which supposition with some alterations 
is also accepted by the Mendelian Theory. Every probability speaks for 
this, that the totality of the gemmulae, respectively genes or factors, which 
run continuously through the series of generations, combining with each 
other by means of the transfer of the gametes in accordance with the chances 
characteristic of the single cases, results in the heredity including atavism 
or reversion and variation also. It seems probable, or almost certain, however, 
that the number of the genes or factors which are at work in the inheri¬ 
tance, is incomparably greater than the believers in the Mendelian Principles 
think ; and, indeed, the infinitely many genes, or factors, in infinitely diffe¬ 
rent and varying proportions according to the cases, according to the pro¬ 
perties of the ancestors, are partly similar and partly different. The ave- 
