TO THE LEACHER 
This book is so arranged as to be adapted either to a brief 
or to a more extended course of study, a double purpose which 
is accomplished by dividing the subject matter into two parts. 
Part I may be taken alone, constituting a brief course covering 
the essential principles that are fundamental to an understanding 
of hereditary transmission and of the business of plant and 
animal improvement. 
Part II can be employed either as additional text or as refer- 
ence matter, at the option of the teacher, and depending upon 
the time that is available. 
In any case, whatever use is made of Part II, either as text 
or reference, it should be in connection with Part I, and not as 
succeeding it; that is to say, Part II should be taken in coz- 
nection with or immediately following the first*three chapters 
of Part I, and this use of Part II is highly recommended, be- 
cause here is a collection of information, not commonly avail- 
able, that throws light not only upon the sources of material 
out of which domesticated races have been made, but also upon 
many of the essential steps in improvement. 
The author is especially anxious that the suggestions and ex- 
ercises offered at the close of the chapters be accepted and fol- 
lowed. Each topic affords material full of interesting and 
profitable study, always from the standpoint of utility; and if 
the students will make some independent studies of this kind, 
they will be doubly repaid not only in the wealth of informa- 
tion accumulated, but in the experience gained in independent 
methods of study. 
With the information afforded in the Appendix the teacher 
will be able to introduce the subject of stock judging. This in- 
troduction should be made early and continued throughout the 
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