184 BOARD OF AGRICULTURE. 



point of vitality. These rythmic actions, once formed, tend 

 to be transmitted under the law of persistence of force, and 

 the conditions involved fall under the laws grouped subor- 

 dinate to inheritance. Hence a general periodicity, exhibiting 

 itself as a law, and race, species, individual periodicity every- 

 where, alike in principle, differing in detail. 



Characters common to many species of a genus are found to 

 resist variation, or to reappear, if lost, more persistently than 

 the characters which are confined to the separate species; * and 

 the longer any character has been transmitted by a breed, the 

 more firmly it will continue to be transmitted.^ These two 

 propositions are essentially similar, as dependent for their 

 establishment on similar facts of observation. In general 

 terms, antiquity of character adds strength. From the con- 

 sideration of the laws involved, we see that each cause must 

 produce a corresponding effect, and as each germ is a concrete 

 force representing the sum of all the forces, whether plus or 

 minus, acting on its past, it must be influenced during each 

 generation by the continued presence of the same concrete 

 force. The truth of this reasoning is illustrated by the facts 

 of evolution, that generic characters are stronger than specific 

 characters ; that individual variability is general, and specific 

 resemblance more constant ; that crossing tends to produce 

 variability, and breeding to pedigree to produce likeness. 

 The apparent exceptions to this law of antiquity of character 

 are numerous ; for whenever, from whatever cause, another 

 force prevails for a season, this prepotency gained from anti- 

 quity in natural course may disappear ; but the fact that this 

 disappearance is oftener in individuals than in species, and in 

 species than genera, illustrates the correctness of our law. 

 Now, the accumulation of forces in one direction, either 

 through a " spontaneous " ( ?) variation or through breeding, 

 may, and often does, introduce a prepotency which will pre- 

 vail over characters which have been assumed during many 

 generations. This is illustrated by the Shorthorn cattle, a 

 comparatively modern breed, which seems prepotent over the 

 majority of the breeds with which they are crossed. The 

 Ancon sheep, as well as the Mauchamp merinos, are illustra- 



* Darwin, An. and PL, under Domest, Vol. I., p. 139. 

 f Darwin doubts, ip. cit., Vol. II., p. 82. 



