Chap, XIV. 



PREPOTENCY OF TRANSMISSION. 



43 



" nearly all the characteristics of the ■white-flowered and white- 

 " seeded varieties ; and this result follows whether these yarieties 

 " have been iise<:l as the pollen-bearing or seed-producing parents." 



The law of prepotency comes into action when species are crossed, 

 as with races and individuals. Gartner has unequivocally shown ^* 

 that this is the case with plants. To give one instance: when 

 JSiicotiana paniciilata and vincoijiora are crossed, the character of 

 N, paniculata is almost completely lost in the hybrid ; but if N. 

 quadrivalvis be crossed with N. vincceflora, this latter species, 

 which was before so prejiotent, now in its turn almost disappears 

 under the power of A\ quadrivalvis. It is remarkable that the 

 prepotency of one species over another in transmission is quite in- 

 dependent, as shown by Gartner, of the greater or less facility with 

 which the one fertilises the other. 



With animals, the jackal is prepotent over the dog, as is stated 

 by Flourens, who made many crosses between these animals ; and 

 this was likewise the case with a hybrid which I once saw between 

 a jackal and a terrier. I cannot doubt, from the observations of 

 Colin and others, that the ass is prepotent over the horse ; the pre- 

 potency in this instance running more strongly through the male 

 than through the female ass ; so that the mule resembles the ass 

 more closely than does the hinny.'* The male pheasant, judging 

 from Mr. Hewitt's descriptions,^'^ and from the hybrids which I 

 have seen, preponderates over the domestic fowl ; but the latter, as 

 far as colour is concerned, has considerable power of transmission, 



^^ ' Basiarderzeugnng,' s. 256, 290, 

 &c. Kaudin (' Xouvelles Archives du 

 Museum,' torn. i. p. 149) givfes a 

 striking instance of prepotency in 

 Datura stramonium v/hen crossed with 

 two other species. 



*^ Flourens, ' Longevite Humaine,' 

 p. 144-, on crossed jackals. With 

 respect to the difference between the 

 mule and the hiuny, I am aware that 

 this has generally been attributed to 

 the sire and dam transmitting their 

 characters difterently; but Colin, 

 who has given in his 'Traite Phys. 

 Comp.,' torn. ii. pp. 537-539, the 

 fullest description which I have met 

 with of these reciprocal hybrids, is 

 strongly of opinion that the ass pre- 

 ponderates in both crosses, but in an 

 unequal degree. This is likewise the 

 conclusioa of Flourens, and of Bech- 

 6tein in his ' Naturgeschichte Deutsch- 

 lands,' b. i. s. 294. The tail of the 

 hinny is much more like that of the 

 horse than is the tail of the mule. 



and this is generally accounted for 

 by the males of both species trans- 

 mitting with greater power this part 

 of their structure ; but a compound 

 hybrid which I saw in the Zoological 

 Gardens, from a mare by a hybrid 

 ass-zebra, closely resembled its mother 

 in its tail. 



*^ Mr. Hewitt, who has had such 

 great experience in raising these 

 hybrids, says (' Poultry Book,' by 

 Mr. Tegetmeier, 1866, pp. 165-167) 

 that in all, the head was destitute of 

 wattles, comb, and ear-lappets ; and 

 all closely resembled the pheasant in 

 the shape of the tail and general con- 

 tour of the body. These hybi'ids 

 were raised from hens of several 

 breeds by a cock-pheasant ; but 

 another hj'brid, described by Mr. 

 Hewitt, was raised from a hen- 

 pheasant, by a silver-laced Bantam 

 cock, and this possessed a rudimeutaj 

 comb and wattles. 



