54 Cattte Problems. 



drawn downward by the weight-force of yield ; as it 

 evidently is, in forming the corrugations or furrows of the 

 twist, in large yielding cows. 



Two cross Sections of the twist, Plate I., Figs. 5 and 6, 

 one showing smooth skin extending over the hollow twist 

 space, the other the corrugated skin extending across a some- 

 what wider space, or twist hollow ; the loose skin meet- 

 ing that which grows close to the body; the junction or 

 Joining of the two, forming a crooked seam, or mane, as 

 it may be called, of rough hair ; some of it upright, and 

 other portions leaning in several different and contrary 

 directions. At these points — the seams, or marginal 

 fringes of the Yield Mark — the influence of weight-strain 

 usually ceases, as appears from the hair beyond them grow- 

 ing in its natural direction. In this manner, the fringed, 

 and more or less curved lines of rough hair enclosing the 

 Yield Mark, are formed, as the effect of the reversed hair 

 meeting and mixing together with the hair that is noi re- 

 versed ; for the reason that the roots of the latter have noi 

 been drawn down by weight-strain, or any other force, 

 out of their natural position and direction. So the fringed 

 edges of the Yield Mark on the upper back-udder skin, 

 are the consequence of milk weight-strain extending to, 

 and terminating at, the boundary lines between the body 

 skin proper and that of the udder-sack, which is coated 

 with reversed hair; the seams, fringes, and boundaries of 

 various sizes of Yield Marks being roughly shown in 

 Plates I. and II. 



The generally close corespondence of size of udders with 

 that of the Yield Marks, also appears in ten figures of the 

 same Plates ; the sizes of udder and Yield Mark being 

 duplicated in Plate I., Figs. 2, 3, 4, and increasing five- 

 fold in Plate II., and its sections — Fig. 6. 



These several combined results of enlarged udders and 

 Yield Marks, result from the concurrent force of increased 



