ROUGH FUR. 



109 



(7) Partial-roughs crossed with smooths of 4-toe or a similar stock 

 give partial-rough young, and also, in most cases, full-rough and 

 smooth young. 



Table 52. 



Crosses (3) to (7) show that full-rough can be recovered from partial- 

 rough usually without trouble, but that partial-rough can not be re- 

 covered from full-rough, either in crossing full-roughs together or with 

 ordinary smooth guinea-pigs (4-toe, etc.). Cross (7) is more significant 

 than appears at first sight. We know that 4-toe smooths transmit 

 nothing which can reduce the grade of roughness. Thus, when we 

 find partial-rough by 4-toe smooth giving partial-rough young, we see 

 that the rough factor and the factor or factors responsible for the low 

 grade of roughness can be transmitted in the same gamete. 



(8) Most partial-roughs crossed with full-roughs give a very similar 

 result to the cross partial-rough by 4-toe smooth, except that fewer 

 smooths are produced. 



Table 53. 



Cross. 



(47) 

 (58) 

 (70) 

 (48) 



Stock and grade. 



A X C (Tri) 



B (Lima) X C (Lima) 



A (4-toe, etc.) X C, D (§, \ cutleri) 

 A (Tri) X E (Tri) 



10 



8 



B 



D 



E 



Sm 



10 

 4 



(9) The lowest grade of roughs (E) very rarely have either a full- 

 rough parent or full-rough young. They also very rarely have a 

 smooth parent of such a stock as 4-toe. 



Of the rough young, 507 have been recorded (excluding 8 from mixed 

 bimaternal litters) ; 413 of these had a full-rough (A, B) or a 4-toe 

 smooth parent; yet these include only 3 rough E young. On the other 

 hand, 13 rough E are included in the 67 rough young from C or D X C ; 

 6 are included in the 11 from C or D X E, 9 are included in the 11 

 rough young from C X smooth Cavia cutleri and all of the 4 rough 

 young from E X E were rough E. Table 54 shows the matings in 

 which one or both of the parents were rough E. These are repeated 

 from other crosses. 



