602 GENETICS IN RELATION TO AGRICULTURE 
Marking Individuals—The problem of marking individuals often is 
difficult where large numbers of individuals are involved. When very 
small herds are kept in which the animals may be known individually 
this matter is not very important, because the animals may simply be 
given a distinctive name, and any notes which it may be necessary to 
make may be recorded under that name. But when individuals become 
more numerous, it is usually necessary to have some safe and effective 
way of distinguishing them. For cattle aluminum ear tags of various 
kinds are often used, and these may be obtained stamped with any numbers 
which are desired. These may be used for smaller animals, also, or the 
ears may be punched in various fashions. A method used by Dr. 
Fie. 234.—Method of identifying sheep by holes punched in the ears. (From the Journal 
of Heredity.) 
Bell in sheep breeding experiments is illustrated in Fig. 234. By the use 
of eight holes with place values such as are indicated in the diagram, it 
is possible to identify 256 sheep according to the following combinations: 
Total sheep identified by 0 hole................ 1 
Total sheep identified by 1 hole................ 8 
Total sheep identified by 2 holes............... 28 
Total sheep identified by 3 holes............... 56 
Total sheep identified by 4 holes..............,. 70 
Total sheep identified by 5 holes............... 56 
Total sheep identified by 6 holes............... 28 
Total sheep identified by 7 holes............... 8 
Total sheep identified by 8 holes............... 1 
This is a very simple mode of identification, and by means of a rubber 
stamp with a sheep’s head outline or description sheets having such 
a head as that shown in Fig. 234 printed upon them, it is very easy to 
record accurately the designation which has been given to any particular 
sheep. The method can of course be used with other animals, and it 
avoids the difficulty of loss which sometimes is met with in using ear tags. 
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