60 
MendeVs Laws of Inheritance. 
Amongst the other characters which have been investigated 
is that of broodiness, and according to Hurst non-sitters, 
when crossed with sitters, give in the first generation all good 
sitters. 
From the studies made with other subjects such as mice, 
rats, rabbits, 1 and guinea-pigs many other examples to illustrate 
the same phenomena might be quoted. It must not be assumed, 
though, that because the cases chosen for description are all 
simple no complications occur, for undoubtedly they do. These 
complications always appear, however, to be capable of analysis 
if only the investigations are made on the right lines, and where 
such investigations have been made they serve to increase one’s 
confidence in the wide applicability of Mendel’s Laws. 
All of the characters quoted are more or less obvious ones, 
and the question might be raised as to whether the same laws 
will hold for such intangible characteristics as, say, docility, 
yield of milk, quality of flesh, and so on. The answer is that 
in all probability they do. Bateson, for instance, after making 
most comprehensive investigations on heredity in poultry 
writes : “ There is no reasonable doubt that such features as late 
or early feathering, shortness of wing quills and tails, peculiar 
qualities of voice, forms of constitutional weakness follow rules 
closely similar to those detected in features more amenable 
to critical study.” 
The inheritance of those characters with which the prac- 
tical breeder will for the most part be concerned is beyond 
the reach of the scientist, who rarely has the opportunity of 
carrying out extended observations of this kind, still more 
rarely perhaps has any interest in those features which go to 
the making up of first class stock. Under these circumstances 
all advance in this particular direction must come from the 
breeder, and he will largely have to work out his own salvation. 
He alone has all the requisite material to hand and is in a 
position to carry out a sufficiently large number of experi- 
ments. 
The chief points to which attention must be paid by any 
one attempting to carry out work of this kind may shortly be 
described here. In the first case, he must become familiar 
with the conception that the animal is built up of a series of 
units or characters, the inheritance of which may be traced 
independently of one another. This offers a certain amount 
of difficulty to those in the habit of judging animals as a 
whole, but this will disappear if such an example as that 
illustrated in Fig. 3 is worked through in detail. Each of the 
characteristics of the two parents should be recorded carefully, 
and their inheritance observed in the cross-breds. As a general 
1 Hurst, Journ. Linn. Soc. Zoology, Vol. XXIX., page 28‘3. 
