HEEEDITY. 



341 



CGM (ANE) 



CNE 



CNM 



pens; the result is quite different and rather paradoxical; the descend- 

 ants of this union all have black eyes, and gray hair upon the back 

 and white upon the belly; 



cg'e ^-. anm 



besides, their eyes are un- 

 doubtedly larger than those 

 of their parents. Their char- 

 acters, on the whole, mark- 

 edly resemble, not at all the 

 gray house mouse {Mus tnus- 

 culiis), but the field mouse 

 (Mus sylvaticus) . Instead 

 of i^resenting the phenome- 

 non of dominance, the paren- 

 tal characters have comhined 

 to produce a new result, a 

 first difference from the Men- 

 delian type described above. 

 I then cross the pseudo field 

 mice resulting from this 

 combination. This time 

 there is obtained an extra- 

 ordinary variety of forms: 

 First, mice that are wholly 

 black ; second, gray m i c e 

 with white bellies, like their 

 parents; third, white mice 

 with red eyes, like one of 

 their grandparents; fourth, 

 yellow^ mice with red eyes, 

 like one of their grandpar- 

 ents; fifth, light gray mice 

 with red eyes. These five forms present fixed numerical relations, 

 which appear to be as follows : In 64 offspring we find : 



r 9 black. 



36 with black eves ■! OT -ii u-* i, n 



•^ \27 gray, with white belly. 



CGM 



o 

 o 

 o 

 o 



ANM 



ag'm 



--etc. 



CGE 



Fig. 3. — Diagram of the crossing of a white mouse (white 

 circle) and a yellow mouse with red eyes (circle with 

 horizontal shading). The hybrids (atavistic forms) 

 resemble the field mouse. The crossing of these hy- 

 brids produces black mice (black circle), gray mice 

 with a white belly (circle with dots), white mice 

 (white circle), yellow mice with red eyes (circle with 

 horizontal shading), and light gray with red eyes (cir- 

 cle with vertical shading). 



28 with red eyes 



16 white. 

 9 yellow. 

 3 light gray. 



It would take too long to explain to you in detail what has hap- 

 pened, but I may say that everything here is merely an application 

 of the Mendelian laws, operating upon three pairs of antagonistic 

 characters ; new combinations have naturally been formed, and these 

 have resulted in the production of unexpected forms, the black and 



