132 HYBRIDISING AND CROSS-BREEDING. 



sterility? I cannot answer those questions, further than by 

 saying that the ways of the All-wise 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 same- 

 ness 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 fertilisation. 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 fertilisation takes place. It is 

 further to be observed that there is frequently an imperfect 

 hybrid fertilisation, 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 H. spedosus ; 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 Rhodora canadensis by Azalea pontica (sections 

 of genus Rhododendron), I saved ultimately only one out of 

 more than one hundred seedlings, and that became a vigorous 

 plant. Such crosses sometimes are a hundred times more deli- 

 cate 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 fertilise the ovule, the 

 stimulus is insufficient, the operation languid, and the fertilisa- 

 tion weak and inadequate to give a healthy constitution. It 

 has been generally observed that hybrid fertilisation is slower 

 than natural fertilisation, and that often a much smaller num- 

 ber of ovules are vivified. The same cause probably operates 

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



