COLOR AND COAT CHARACTERS. 23 



To put this matter in concrete form, table 13 has been drawn up. 

 In this table all mothers and young are classified as ticked-bellied, 

 dark-bellied, or light-bellied animals. The correlation existing between 

 the ventral and the dorsal sides allows the inference that the shade of 

 agouti on the back of animals classified as ticked is the darkest, whereas 

 the back of animals marked light is the lightest, and an intermediate 

 category, dark, falls in between these two. The animals which had 

 the hair on the belly barred with yellow, but with hair-tip and base 

 dark, were called ticked-bellied, and these animals were the darkest 

 hybrids, both dorsally and ventrally. A few animals were called dark- 

 bellied which had hair on the belly that was yellow at the tip but had 

 much black at the base. Those animals in which the hair on the belly 

 was entirely yellow or yellow with little black at the base were classified 

 as light-bellied. These last were the lightest animals dorsally and 

 ventrally and resemble the domestic guinea-pig closely. All the mothers 

 were heterozygous in agouti, having received their agouti factor from 

 one parent, the wild, or the wild hybrid. They were mated to non- 

 agoutis and produced equal numbers of agouti and non-agouti offspring, 

 and have been discussed in this light under tables 6 to 11. Now, table 

 13 shows that these same agouti offspring were of variable character. 

 The recessive non-agouti offspring are here disregarded. 



The Cavia rufescens had been mated with guinea-pig females, and 

 yielded all agouti offspring. The records show that 11 were very dark 

 with ticked bellies, 1 dark with dark belly, and 2 light with light bellies. 

 Just what the rest were can not be told, for they died young or were 

 aborted. The | wild used as mothers of the | wild had ticked bellies, 

 and are entered on the first line of table 13. In spite of their dark 

 color they produced only 18 like themselves (43 per cent), 5 intermedi- 

 ates, and 19 Ught agoutis. The | wild with ticked belly transmitted 

 their character to a large proportion (90 per cent) of their offspring, 

 producing 19 ticked bellies and 2 light. The i wild with ticked bellies, 

 and all hybrids thereafter, produced only ticked-belly offspring (100 

 per cent). Since the construction of the table, new experiments with 

 fertile hybrid -^ and ^4^ wild males show that these also transmit 

 the very dark agouti with ticked belly to their offspring, irrespective 

 of whether they are mated to I wild non-agoutis or to guinea-pig 

 non-agouti or whether they are fathers of y^ ^Id, or t4t ^d, or -^ 

 wild. 



The dark-bellied females used were only two in number, both I wild 

 animals; one produced a dark-bellied young one and the other a light- 

 belUed one. They evidently do not always transmit agouti just like 

 their own, but nothing can be said further than that. 



The light-bellied females also fail to transmit in all cases agouti which 

 acts just as their own; for the i wild mothers with light bellies gave 

 7 ticked-bellied young (41 per cent) and 17 light bellied young. The 



