OBSERVATIONS UPON MUIJNG AMONG PLANTS. 7 



place must be unequal, and that there can be no question about 

 equivalence of factors. Even in the intermediate hybrids, where 

 the formative powers are so -intimately blended, there is still 

 generally some particular organ which shows the prevalence of 

 the one factor over the other. 



We cannot trace the origin and development of the different 

 vegetable forms, from the simple cell to the complete develop- 

 ment of the perfect vegetable, through all its phases ; much less 

 can we distinguish the connection between the changes wrought 

 by hybridization, and normal vegetable metamorphoses. It is 

 very doubtful, indeed, whether vegetable anatomy, improved as 

 it may be, will ever be in a condition to estimate such vital pro- 

 cesses. We must rest content, therefore, with the knowledge of 

 the mere facts of the case. New characters sometimes arise in 

 hybrids entirely distinct from those existent in the parents, so 

 that they might reasonably be taken for distinct species. Hybrid 

 forms of Mirabilis exhibit such changes in a very surprising de- 

 gree, as does also the genus Rhododendron, and curious instances 

 may be adduced of marked alterations of form and condition in 

 almost every organ. 



In few characters is the influence of muling more striking 

 than in the size and colour of blossoms. In many closely allied 

 species, which diifer but little in habit or foliage, the colour of 

 the corolla is of great importance. In a wild state it is for the 

 most part constant, and is often indicative of distinct groups or 

 species. In other groups, on the contrary, it is extremely vari- 

 able, and is notably different at different periods of growth. 

 Where, however, colour is the most constant and distinctive, 

 union is often practicable, and in general tlie consequence of 

 hybridization is a complete derangement of the laws on which 

 such constancy of hue depends. Neither are the hues resulting 

 from the union necessarily intermediate. Blue and yellow, for 

 instance, do not produce green, as is proved by Verbascum 

 jyhceniceum and phlomoides. Gladiolus cardinali-blandus ex- 

 hibits the less brilliant hue of the male parent rather than the 

 splendour of the mother ; and in some cases the tone of colour 

 of one of the parents is exhibited under a more brilliant tint, as 

 in Nicotiana suaveolenti~gluti?iosa. 



Sometimes the change of colour is exhibited in an increase of 

 the number of typical forms arising from any particular union. 

 Geum canadensi-coccineum, for instance, gives a larger number 

 of hybrids witli ample orange-coloured flowers, mixed with a 

 small proportion of pale yellow. Mr. Herbert raised from Rho- 

 dodendron ponticum and Azalea j)ontica two specimens with 

 yellow scented flowers like those of the Azalea, one with lemon 

 coloured, and one with a chestnut-brown tint intermediate be- 

 tween the purple and yellow of the parents. In reversed im- 



