THE BREEDING OF ANIMALS, IN GENERAL 73 



Kinds of variation. — Since variation extends to each char- 

 acter, it may aid us in a clearer understanding of variation among 

 farm animals if we consider the subject from four points of 

 view. First, we will consider that variation may be expressed 

 only in form and size. This is quantitative variation, having to 

 do with degree only. Such variation is the simplest form, and 

 we observe evidences of it on every hand. For example, of 

 two horses of the same breed, one may be large, the other small ; 

 on the same animal one foot may be larger than the. others ; the 

 two ears may not be of the same size; one eye may be larger 

 than the other. Between two dairy cows of the same breed, 

 one may have a very large, well-proportioned udder, the other 

 small and irregular in shape. Illustrations' of the first class are 

 without number. The second class of variation is that which is 

 expressed in the quality, as distinct from form and size. This 

 is qualitative variation; that is, having to do with characters 

 only. Evidences of this are also abundant. For example, of 

 all the cows in existence, no two yield milk containing the same 

 amount of fat; in fact, the individual cow varies widely from day 

 to day in the percentage of fat contained in the milk. Again, 

 no two pieces of beef are exactly alike in flavor, tenderness, 

 juiciness, and the like. The quality of no two horses is alike, — 

 one has coarse, rough hair and a thick hide, the other has smooth, 

 soft hair and a smooth, pliable hide. The third class of varia- 

 tion has to do with the function or with the activity of the vari- 

 ous organs and parts of the body, such as muscular activity, 

 glandular secretions, and the hke. There are many examples of 

 this, such as variation in the milk flow, some cows yielding as 

 high as 128 pounds in a single day; variation in the fertility, 

 some cows producing only four or five young in their hfetime, 

 while the Angus cow Old Granny (No. 1 of the Angus Herd 

 Book) produced twenty-five, the last one in her twenty-ninth 

 year; variation in speed, scent, and in fact all functions. 

 The fourth class of variations has to do with deviations from 



