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Dec. 10,1917 Nature and Rate of Growth in Lambs 
609 
planes: 1 One formed by length with vertical measurements and the other 
by length with transverse measurements. Length includes four units: 
(1) Head, (2) neck, 2 (3) trunk, and (4) croup. Height includes four: (1) 
Total height, (2) chest depth, (3) foreleg length, and (4) hindleg length. 
These transverse measurements were taken: (1) Head width, (2) chest 
width, and (3) loin width. The uniformity of the correlations shown in 
Table III suggests that loin and chest widths reflect either directly or by 
correlation the relation in variability between length and width. 
CONFORMATION 
Accepting the length of the vertebral axis as the best linear dimension 
with which to compare other linear dimensions, we can separate it into 
three distinct divisions: (1) The head, (2) the neck, and (3) the trunk. 
From the economic point of view the first two of these divisions are 
unimportant, since they contribute no material value to the carcass; nor 
would any variation in their conformation within normal limits produce 
any material change in the quantity of fleece. 
Conformation is essentially expressed by proportions, in which size as 
a whole plays no part. It is a term expressing only dimensional relations, 
of which the ratio of length to breadth and depth are the most important. 
In a general way conformation may be divided into four types. 3 Assum¬ 
ing that we have four animals of equal trunk length, we may designate 
these classes as (1) those with relatively deep but narrow bodies; (2) those 
with relatively broad but shallow bodies; (3) those with bodies that are 
relatively both deep and broad; and (4) those with bodies that are both 
shallow and narrow. By these types as a basis we are able to express the 
general traits of conformation of an animal. 
What the specific effect of any variation in ratio of depth to length or 
of width to length has on the development of two of the major traits 
(constitution and mutton form) of an animal remains still to be estab¬ 
lished empirically. Experiments under way here along this line suggest 
that relative depth of body is the most important if not a perfectly 
satisfactory index of constitutional development. 4 On the other hand, 
it is also found that thick flesh, while always associated with relative 
1 These planes are also used to contrast differences in conformation. 
2 Of all dimensions this is the most difficult to obtain with accuracy. 
3 These of course represent extremes between which we find all possible degrees of intermediates. 
4 This is based on the assumption that a chest cavity which is deep in relation to body circumference 
is associated with relatively larger internal capacity for performing its vital functions and a consequent 
greater constitutional vigor. In explanation of this point it may be added that cross sections of a number 
of different types of animals show entirely different results from internal measurements of cross sec¬ 
tions than might be expected from external measurements. While external measurements are a good 
index to internal conditions, they may easily be misinterpreted in animals with a heavy covering of flesh. 
Furthermore, an animal may be capable of developing a high degree of mutton (with good care and feed) 
and not possess the desirable degree of constitutional vigor, or the reverse condition may be found as 
well. 
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