SYLLABUS OF LECTURES 
ON THE 
LAWS OF HEREDITY 
AND 
Principles of Breeding. 
GIVEN AT THE SHEFFIELD SCIENTIFIC SCHOOL OF YALE COLLEGE, 
TO STUDENTS IN THE COURSES IN AGRICULTURE AND IN 
BIOLOGY, JANUARY TO APRIL, 1878, BY WM. II. BREWER. 
(This Synopsis of Topics, numbered in the order of their treatment, is printed 
for the convenience of the class.) 
I. INTRODUCTION. 
1. The breeding and rearing of animals the most universal of 
vocations and fancies. 
2. The two great ends of Modern Agriculture are the produc- 
tion of animals and the production of crops. 
3. The part that Domestic Animals play in Modern Agricul- 
ture. 
4. Breeding as an Art is very ancient. 
5. The intelligent application of scientific theories and biolog- 
ical laws to breeding is wholly modern. 
6. This course of lectures relates to the principles which 
underlie the modern art. 
7. Qualifications necessary for high success as a practical 
stock breeder. 
8. Definition of Domestic Animals. 
c- 
9. Wherein they differ from merely tamed ones. < 
10. The nature and function of Instincts. 
11. What characters domestication necessarily implies. 
12. Most animals can be tamed ; but few are domesticated. 
Classification of Domestic Animals. 
13. Those hred for fancy, or as pets and companions of man. 
14. Those bred for their products. 
15. Those hred for their flesh. 
16. Beasts of burden. 2 
17. Those bred for man’s games and sports. 
18. Those bred for various other purposes. 
19. Profit and Fancy are the incentives. 
20. Certain general laws apply in breeding all these classes. 
21. Relations to the Human Race. 
22. Some Technical Terms defined. 
23. A rapid sketch of the main parts of our subject. 
II. HEREDITY. 
24. Definition. 
25. Relations to species, races, breeds and tribes. 
26. Heredity of individual peculiarities. 
27. Potency and “ Prepotency.” 
28. Some causes which modify the force of heredity. 
29. What characters are most often transmitted by heredity. 
30. Heredity of bad points as well as good ones. 
31. Practical relations of heredity to antiquity of race. 
32. Practical relations to purity of breed. 
33. Heredity of diseases. 
34. Mutilation usually not hereditary unless disease results. 
35. Heredity of acquired characters. 
36. Relations to Education, Training and Instinct. 
37. Some relations of Heredity to social problems in human 
society. 
38. “Constitution,” what it is. 
39. Atavism, or Reversion. 
III. VARIATION. 
40. Variation is as universal as heredity, hut less in degree. 
41. Plasticity, or the capability of being moulded. 
42. Variations resulting from the character and relative abund- 
ance of food and drink ;—nutrition. 
43. Variations induced by climate and exposure. 
44. Variations induced by soil and topography. 
45. By natural enemies, animal and vegetable. 
46. Regional influences. 
47. Variations which may be reasonably predicted from known 
conditions, that is, from the 11 environment.” 
48. These usually slight in a single generation, but often very 
important to the breeder. 
49. By man’s protection, care and training. 3 
50. Variations resulting from causes or conditions as yet un- 
known, '''‘spontaneity.'1'1 
51. These may be either slight or great in a single generation. 
52. The appearance of new characters. 
53. The sudden and wide variation known as “ sporting.” 
54. Alleged sporting often merely atavism. 
55. Variation often accompanies crossing. 
IV. SOME RELATIONS OF HEREDITY TO VARI- 
ATION. 
56. Some of the characters acquired by the parent through 
variation, are usually transmitted to the offspring. 
57. All of them occurring in any individual are never absolutely 
and entirely transmitted, hence perpetual variety. 
58. The special peculiarities of sports are often practically 
transmitted entire if transmitted at all. 
59. New breeds of Domestic Animals rarely originate in sports. 
60. New varieties of cultivated plants often so originate. 
61. Theory of the immutability of species. 
62. Limitation of variation according to this theory. 
63. Theory of the mutability of species. 
64. Relations of variation to this theory. 
65. Hypotheses relating to variation. 
V. BREEDS AND PEDIGREES. 
66. The nature of breeds, races, varieties and tribes. 
67. Thoroughbreds, Grades, Cross-breeds, Hybrids, “ Mongrels,” 
“Natives,” “Scrubs,” &c., defined. 
68. Pedigrees. 
69. Stud-books, Herd-books, Registers and Records,—their 
character and uses. 
VI. CLOSE BREEDING. 
70. Relations of purity of breed to special excellencies, and to 
success in practical Stock-breeding. 
71. Bakewell’s experiments and experience. 
72. The Collins’ Brothers and their Shorthorns. 
73. Breeding “ In-and-in,”—definition. 
74. Illustration from certain Shorthorn pedigrees. 
75. Ditto,—from Setter dog pedigrees. 
76. Relations to atavism. 4 
77. Alleged advantages for “fixing characters.” 
78. For increasing family force of “ prepotency.” 
79. For “concentration of blood.” 
80. For uniformity of type. 
81. For augmenting excellencies. 
82. Other alleged advantages and uses. 
83. Limitations and dangers. 
84. Alleged effects on constitutional and sexual vigor. 
85. These alleged effects very unequally developed in different 
breeds. 
86. Suggestions from Nature. 
87. Relations to certain sanitary problems in human society. 
88. Breeding “ in line.” 
VII. CROSSING. 
89. Various uses of the term. 
90. Relations of out-crossing to health, vigor, constitution and 
fertility. 
91. “Nicking.” 
92. Conflicting hypotheses as to breeding between like parents 
and unlike parents. 
93. Hybrids, their characters. 
94. Violent crossing;—its relations to health, vigor and fertility. 
95. Relations of crossing to atavism and to spontaneous variation. 
96. Relations to mental character, temper and disposition. 
97. Instability of grades and cross-breeds. 
98. “Mongrels,” “Natives,” &c., again noticed. 
99. French experiments with sheep. 
100. Facts concerning crossing the human races. 
(Crossing for other special ends will he discussed later.) 
VIII. BREEDING TO POINTS. 
101. Breeding to Points;—definition. 
102. The geometrical ratio of increase among animals makes a 
wide range of selection possible. 
103. The improvement of breeds by the selection of parents 
having valuable points. 
104. “Weeding.” 
105. Whatever may be the origin of breeds, this is the universal 
method of improvement. 
106. Points and “Scales of Points.” 
107. “ Ideal Types.” 5 
Illustrations from Swine. 
198. The Wild Boar. 
109. How changed to the Domestic Hog. 
110. What changes in structure have followed. 
111. What changes in instincts and habits. 
112. Modern improved breeds. 
Illustrations from the Race Horse. 
113. The horse of antiquity. 
114. The English Horse of the Middle Ages. 
1 15. The horses of Modern Arabia, Turkey and Barbary. 
116. The English Thoroughbred. 
117. Horse Racing. 
118. Stakes and prizes won in races have been the strongest 
special incentive to improvement. 
119. Magnitude of the winnings of some successful horses. 
120. Character of the competition. 
121. Nature of the problems involved in breeding Race Horses. 
122. Character of the changes believed to have been made. 
123. Record of mile races and mile heats. 
124. Record of two and four mile races and heats. 
125. The limit of speed is perhaps nearly reached. 
126. Number of horses with records near the best. 
127. Value of these illustrations because we have so full a 
history. 
128. Other benefits than speed that have been incidental to this 
progress. 
Illustrations from Trotters. 
129. The history of American Trotters. 
130. The records of increase of speed since 1830, to illustrate 
the principle. 
131. Further illustrated by the large number of 2.30 trotters. 
132. Anatomical, physiological, psychical and mechanical prob- 
lems involved in this improvement. 
133. Relations to heredity, training and care. 
134. Russian Trotters. 
Illustrations from other Breeds of Horses. 
135. Roadsters. 
136. Draught horses. 6 
137. Ponies. 
138. Indian horses; mustangs; half wild horses. 
139. Regional influences on horses; horses of mountains; horses 
of islands. 
140. Special points that are independent of breeds. 
Illustrations from various Breeds of Cattle. 
141. Breeds for beef. 
142. For milk, cream, butter and cheese. 
143. For other special uses or special conditions. 
Illustrations from Sheep. 
144. The species only known in the domestic breeds. 
145. Great number and variety of breeds. 
146. Breeds for combing-wools. 
197. For felting-wools. 
148. For special classes of fabrics. 
129. For mutton. 
150. For milk, butter and cheese. 
151. Breeds used in semi-barbarous countries. 
152. Some political and speculative phases of sheep-breeding. 
Illustrations from Dogs. 
153. The great number of breeds. 
154. The wonderful variety of characters produced by breeders 
and fanciers. 
155. IIow size, form, structure and color have been modied. 
156. How natural instincts have been changed and artificial 
instincts formed. 
Illustrations from various species. 
15 V. Goats. 
158. Rabbits. 
159. Fowls, Turkeys, Geese, &c. 
160. Pigeons. 
161. Canary birds. 
162. Illustrations from other species bred for pets or fancy. 
163. Certain general biological laws underlie and control all 
the phases of breeding above mentioned. 
164. But the details of the breeders’ art vary very widely in 
actual practice with different species and breeds. 7 
165. Disposition, temper and artificial instincts as points to be 
bred for. 
166. Bad points may be as surely bred to as good ones. 
167. Too much attention often paid to fancy points and “style” 
in breeding animals of utility. 
168. Relations of breeding to points, to pedigree. 
169. Selection and weeding not to be neglected because of ped- 
igree. 
170. The element of time necessary for the changes and im- 
provements described. 
171. Antiquity of some breeds. 
172. Relation of this section to human races and tribes. 
173. Relation to “ Natural selection.” 
IX. LIMITATIONS OF BREEDING TO POINTS. 
174. Improvement cannot be continued indefinitely in any one 
direction. 
175. Correlations of growth. 
176. Explanation of how certain defects are parallel to and 
increase with improvements. 
177. Illustrations where such correlations are from obvious 
causes or obvious dependence. 
178. From sheep,—relations between character of the wool and 
the flesh,—between the fineness of the fibre and hardi- 
ness. 
179. From horses,—form and strength,—texture of bone and 
speed. 
180. Illustrations from Poultry. 
181. Other illustrations and examples. 
182. Correlation where the cause of the dependence is not 
obvious. 
183. “ Signs” of qualities. 
X. ANTENATAL INFLUENCES 
184. Conception, Embryology and Gestation. 
185. Influence of fright, fear, etc., in the dam on the offspring. 
18C. Other facts and phenomena,—“ Imagination.” 
187. Influence of the first offspring on the dam. 
188. Attempts to control the production of the sexes. 
189. At what age should animals breed ? 
190. Various influences which modify conception and fertility 
191. Deformities and Monstrosities. 8 
XI. RELATIVE INFLUENCE OF SIRE AND DAM 
192. Their relative influence on the improvement of a herd, or 
on the stock of a district. 
193. The sire most potent in such improvement in all polyga- 
mous breeds. 
194. Their relative influence on the individual offspring. 
195. Various hypotheses and theories that have been proposed. 
196. The theory of Linnaeus. 
197. Its revival and extension by Orton. 
198. Application of these theories. 
199. Influence of the relative size of sire and dam. 
200. Influence of the relative age of sire and dam. 
XII. CROSSING FOR SPECIAL USES. 
201. The nature of grades and cross-breeds considered in 
respect to individual excellence for special uses. 
202. Crossing cattle for beef, draught, milk, etc. 
203. Crossing sheep for special demands of the market. 
204. Crossing horses for various immediate special results. 
205. Other crosses for special uses. 
206. The production of thoroughbreds to be used in making such 
grades and cross-breeds. 
XIII. PROFITABLE ADAPTATION OF BREEDS 
TO LOCALITIES AND CONDITIONS. 
207. The local origin of breeds. 
208. Why breeds that are profitable in one place are often 
unprofitable in another. 
209. The most improved breeds are very artificial productions 
which have been specially bred and adapted to particular 
conditions and uses. 
210. Their technical superiority only kept up by good breeding 
and special care. 
211. Hence the relation of breeds to the habits and skill of the 
owner, as well as to the natural and economical condi- 
tions of the locality. 
212. There is no “ horse for all work,” nor is there among other 
animals any breed best for all uses. 
213. The highest profit is reached only when special breeds for 
special purposes are used. 
214. Each region must determine for itself by the experiment 
of actual use what breeds are most profitable for it to 
produce.