ON HYBRIDIZATION AMONGST VEGETABLES. 



11 



with much difficulty, and, when obtained, are rather disposed to 

 sterility ? I cannot answer those questions, further than by say- 

 ing that the ways of the Allwise are past finding out : but I can 

 surmise that in the genus Hippeastrum there is a great sameness 

 of constitution, and that the pollen finds in the style exactly that 

 which is requisite for the growth and development of its tubes, 

 and that the pollen of a fresh individual with the same chemical 

 properties gives a more powerful stimulus, as the introduction of 

 a fresh cross has been found to do amongst animals ; and that in 

 the two other genera there is less sameness of constitution, greater 

 difference in the proportions of the component parts of their juices, 

 and the pollen is not suited with what it wants for the purposes of 

 fertilization. I suspect, therefore, that it is by the nice adaptation 

 of the juices of each individual type to yield the exact proportion 

 of what is wanted for the pollen of its kind, that the Almighty 

 has limited the races of created things ; and that, wherever that 

 adaptation is perfect, a perfect offspring is produced. Where it 

 is not perfect, an inadequate or a weak fertilization takes place. 

 It is further to be observed that there is frequently an imperfect 

 hybrid fertilization, which can give life, but not sustain it well. 

 There are several crosses which I have repeatedly obtained, but 

 could not raise the plants to live for any length of time. I 

 obtained much good seed several years ago from Hibiscus palustris 

 by speciosus ; I sowed a little each year till it was all gone ; the 

 plants always sprouted, but I saved only one to the third leaf, 

 and it perished then. I have never raised beyond the third or 

 fourth leaf a cross between Rhododendron ponticum and an orange 

 Azalea, though I have saved two or three through the first winter. 

 My soil, however, is very uncongenial to them, and under more 

 favourable circumstances they would have been saved. From Rho- 

 dora canadensis by Azalea pontica (sections of genus Rhododen- 

 dron), I saved ultimately only one out of more than a hundred 

 seedlings, and that became a vigorous plant. Such crosses some- 

 times are a hundred times more delicate in their first stage than 

 natural seedlings. Mr. Bidwill, in attempting crosses at Sydney, 

 has also (as he informs me) raised some with difficulty, which have 

 invariably perished. In these cases I apprehend that, although 

 the affinity of the juices is sufficient to enable the pollen to fer- 

 tilize the ovule, the stimulus is insufficient, the operation languid, 

 and the fertilization weak and inadequate to give a healthy con- 

 stitution. It has been generally observed that hybrid fertilization 

 is slower than natural fertilization, and that often a much smaller 

 number of ovules are vivified. The same cause probably operates 

 in that respect : the affinity not being perfect, the necessary in- 

 gredients are attracted by the pollen less readily and insufficiently, 

 and by many of the grains not at all. 



