Variations in Yield Mark. 53 



row ; and so with the twist, or liollow space between the 

 thighs ; accordingly, the entire breecli figure is narrower ; 

 the Yield Mark, also, being narrower, and extending 

 higher towards the vulva, in tall cows. This difference in 

 width and hight of the breech-growth causes wider or 

 narrower twists; which explains why Yield Marks, of 

 regular outline, and about equal in their ioiai size, so fre- 

 quently vary in width and hight. For instance, in Plate 

 I., the marks from i to 4 are shorter and somewhat wider 

 than those on the taller figures, in proportion to hight of 

 the cows and breech-figures — ^i to 5, Plate II. The 

 udder, also, is narrower and deeper, generally, in cows 

 with narrow breech-growth ; and wider, with less depth, 

 in those of wider form ; which accounts for the difference 

 of width and hight of Yield Marks of the same or equal 

 area of hair-surface ; the same area of reversed hair being 

 formed, generally, by the same extent of milk-weight, 

 whatever the outline form of the Yield Mark may be. 

 Thus Fig. 4, Plate I., though wider and shorter, is of 

 equal surface extent with Fig. 4, Plate II., which is nar- 

 rower and higher ; regular or usual outline forms being 

 here considered. And as will appear, form and propor- 

 tions of breech-figure growth have much influence in 

 varying the outline form — but not on the total area, or 

 size, of the Index of yield ; or reversed hair mark. 



The corrugations, or furrows, in the upper part of the 

 bag, are apt to be deeper in tall cows, with deep udders, 

 than in the same part of low cows; from the same degree 

 of strain, from yield -weight; drawing down upon a nar- 

 rower portion of twist- skin; the downward tension of the 

 yield-weight, being the force, and cause, which furrows 

 the Yield Mark or loose skin of the twist. And, it is 

 repeated, as important to remember, that the inner skin 

 layer under the Yield Mark is only loosely attached to 

 the flesh, so as to move freely, as otherwise it could not be 



