Chap. XXIII. CONDITIONS OF LIFE. 277 



of TTyhhcus syriacus from seed collected in South Caroliua and the 

 Holy Land, where the parent-plants must have been exposed to 

 considerably different conditions; yet the seedlings from both 

 localities broke into two similar strains, one with obtuse leaves and 

 purple or crimson flowers, and the other with elongated leaves and 

 more or less pink flowers. 



We may, also, infer the prepotent influence of the constitution of 

 the organism over the definite action of the conditions of life, from 

 the several cases given in the earlier chapters of parallel series of 

 varieties, — an important subject, hereafter to be more fully dis- 

 cussed. Sub-varieties of the several kinds of wheat, gourds, peaches, 

 and other plants, and to a limited extent sub-varieties of the fowl, 

 pigeon, and dog, have been shown either to resemble or to differ 

 from one another in a closely corresponding or parallel manner. 

 In other cases, a variety of one sjDecies resembles a distinct species ; 

 or the varieties of two distinct species resemble one another. 

 Although these parallel resemblances no doubt often result from 

 reversion to the former characters of a common progenitor ; yet in 

 other cases, when new characters first appear, the resemblance must 

 be attributed to the inheritance of a similar constitution, and con- 

 sequently to a tendency to vary in the same manner. We see 

 something of a similar kind in the same monstrosity appearing and 

 reappearing many times in the same species of animal, and, as Dr. 

 Maxvvell Masters has remarked to me, in the same species of plant. 



We may at least conclude, that the amount of modification 

 which animals and plants have undergone under domestication 

 does not correspond with the degree to which they have been 

 subjected to changed circumstances. As we know the parent- 

 age of domesticated birds far better than of most quadrupeds, 

 we will glance through the list. The pigeon h-is varied iu 

 Europe more than almost any other bird ; yet it is a native 

 species, and has not been exposed to any extraordinary change 

 of conditions. The fowl has varied equally, or almost equally, 

 with the pigeon, and is a native of the hot jungles of India. 

 Neither the peacock, a native of the same country, nor the 

 guinea-fowl, an inhabitant of the dry deserts of Africa, has 

 varied at all, or only in colour. The turkey, from Mexico, 

 has varied but little. The duck, on the other hand, a native 

 of Europe, has j^elded some well-marked races ; and as this 

 is an aquatic bird, it must have been subjected to a far more 

 serious change in its habits than the pigeon or even the fowl, 

 which nevertheless have varied in a much higher degree. 

 The goose, a native of Europe and aquatic like the duck, has 

 34 



