INFLUENCE OF TEMPERATURE, 39 



yolk lessens in quantity, which is followed by compara- 

 tively a hard, inelastic, unyielding character of the wool, 

 with the strength and weight greatly diminished. There- 

 fore, notwithstanding the singular longevity of these breeds, 

 it is better to pass them over to the butcher, when arrived 

 at the age mentioned. 



Intimately connected with producing a sound and true sta- 

 ple, is the 



INFLUENCE OF TEMPERATURE. 



It cannot be doubted that equability of temperature is an 

 important agent in perfecting the several properties of wool. 

 The Spanish custom, continued for centuries, of driving the 

 sheep in the spring to the northern and mountainous parts 

 of the kingdom, which are there kept until the approach of 

 winter, originated in part from the conviction that this theory 

 was sound. Indeed, it is founded in the natural instinct of 

 the sheep. Every one knows it is impatient of heat. In 

 the midst of summer, in all latitudes where it is found, it 

 will seek the most elevated points for the sake of the cool- 

 ing breeze, and retire to shades to guard itself against the 

 burning rays of the sun. In winter it will flee to a place of 

 refuge from storms and cold. All this testifies strongly in 

 favor of the correctness of the premises. But the question 

 may be asked, what has the bodily comfort of the animal to 

 do with perfecting the several properties of the fleece ? The 

 answer is, every thing. If health and thrift are promoted 

 by equability of temperature, the cutaneous glands are alike 

 healthy, and a regular and even growth of the fibre naturally 

 follows. 



But strictly speaking, equability of temperature is nowhere 

 to be found ; therefore, in our rigorous and changeable climate, 

 the fibre of w^ool must ever present a greater or less inequal- 

 ity of diameter between its extremes. It is remarkable that 

 the point has always the largest bulk. This is the product 

 of summer, after shearing time, when there is a repletion of 

 the secretions which produce the wool, and when the pores 

 of the skin are relaxed and open, and permit a larger fibre 

 to protrude. The portion near the root is the growth of the 

 spring, when the weather is getting warm ; and the inter- 

 mediate part is the offspring of Avinter, when, under the in- 

 fluence of the cold, the pores of the skin contract, and permit 

 only a finer fibe to escape. 



