152 ARTIFICIAL FERTILISATION 



found that of the Aucuba inert after being stored about six 

 weeks. But as some bits of stems had got mixed, these may, 

 by inducing damp, have destroyed it. I would therefore 

 recommend it to be brushed off pure and stored in silk-paper. 

 I notice this result here (somewhat out of place) to suggest the 

 propriety of storing, and, if needful, of importing pollen, which, 

 if wrapt up in silk-paper, might even, enclosed in a letter, reach 

 this country still potent, by the overland route from India, or 

 after two or three months' voyage, from all parts of South and 

 North America. Let collectors and friends in distant countries 

 be instructed as to this, and we may soon have an improved 

 progeny of the rarest things, even before such novelties from 

 which they are derived have been obtained from their own 

 seeds in this country. 



6th. There is another matter of much consequence to be 

 attended to in the crossing of distant species I mean, the 

 times and seasons for effecting the cross ; yet not one of those 

 most experienced in the art, from Darwin downward, has 

 touched upon this point. It has been forced upon my atten- 

 tion for more than twenty years. I have found that I could, 

 on some few propitious days which occur throughout the 

 season, successfully effect crosses I could not effect with all my 

 care at other times. I have adverted to this in the paper I 

 formerly submitted to you, and I again refer to it. There are 

 some crosses which I have effected at such times, and which I 

 would have tried in vain to accomplish at times less favourable. 

 If you have, say two plants of Rhododendron, one a tiny thing, 

 to cross with a large species, or if you wish to attempt a cross 

 between an Indian Azalea and a Rhododendron, watch for a 

 propitious time. Such times occur, often few and far between, 

 when there is less of sun than of that latent form of heat which 

 frequently occurs before thunder, from the air being more than 

 ordinarily charged with electricity. Or they may occur in the 

 spring season, when there is much ozone present, whose influ- 

 ence I have often found to tell most favourably in promoting 

 the germination of long-sown seeds. It was to the presence of 

 ozone, or to some other form of electrical agency, I attributed 

 the almost simultaneous germination of some New Zealand 

 seeds of a shrub which I got from that country under the name 

 of " Black Maupan," a species of Pittosporum, which sprang 

 up together on the morning of the i6th March 1863, after they 

 had lain dormant two years and eight months. Such atmo- 

 spheric conditions, to whatever cause they may be due, I have 

 found not unfrequently to occur with the east winds of March 

 and April ; at which times I have seen many other long-sown 



