The sheep : its external structure & internal organs / by A. Seyfferth ; revised and edited by G.T. Brown.

  • Seyfferth, A.
Date:
[1896?]
Catalogue details

Licence: Public Domain Mark

Credit: The sheep : its external structure & internal organs / by A. Seyfferth ; revised and edited by G.T. Brown. Source: Wellcome Collection.

    14/30 page 10
    was recorded by the writer more than thirty years ago, and since then they have been met with at twenty months. Fig. 9.—Incisors of Sheep at Three Years Old, showing recently cut Corner Teeth. Dentition in sheep is completed by the eruption of the corner permanent incisors, which are usually cut at the age of three years, as shown in the above drawing. In some cases the corner teeth are not well up till the animal is nearly four years old, so that there is a possibility of a mistake being made as to the age to the extent of a year, by an examiner who contents himself with an inspection of the corner incisors. No diffi- culty, however, would be experienced in deciding whether the corner incisors represent three years or four years, if the state of the other incisors is taken into account. At four years of age the six broad teeth will show marks of wear; the central incisors especially will be worn hollow on tlieir upper surfaces, the middles and laterals also showing well-marked tables in the place of sharp-cutting edges; while the recently cut corner incisors, supposing their eruption to have been delayed till the sheep was nearly four years old, will present a marked contrast to the rest of the teeth which have suffered from attrition. These appearances are shown in the next drawing (Fig. 10) of the mouth of a sheep at the age of four years. Fig. 10.—Incisors of Sheep at Four Years. After the age of four years, and indeed from the time of the com- pletion of permanent dentition, whether early or late, the changes which are effected in the form of the incisors by wear vary according to the nature of the food, and the examiner must be content to limit his inquiries to the period within which is comprised the eruption of the permanent teeth. CONFORMATION. It was stated in the companion work on the Ox that the form of the animals intended for food had undergone considerable modifica- tions under the influence of artificial selection. The sheep is not an exception to the rule. By careful selection the breeder has suc- ceeded in producing sheep which, however they may vary in size, the perfection of form is deemed to be that which will admit of the deposit of fat and flesh of the best quality, to the exclusion of offal and the less favourite parts.
    digitised image 1
    digitised image 2
    digitised image 3